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Purpose: To evaluate the impact of removable partial dentures (RPDs) on masticatory performance (MP) of partially edentulous subjects., Materials and Methods: Electronic database and hand searches were conducted to explore clinical trials reporting the evidence of the effect of metal- and acrylic-based RPDs on mastication. The validated objective and subjective measures of assessment of mastication were included. The article selection, data extraction, and assessment of risk of bias were conducted by two reviewers independently., Results: Out of 11,200 studies, 1 randomized controlled trial and 23 clinical trials met the inclusion criteria. Positive impact on different parameters of masticatory function after RPD treatment was reported in 14 studies. Subjective evaluation of chewing ability (CA) displayed an improvement in 83.3% of studies, while improvement was evidenced only in 69.5% of studies upon objective evaluation. Most studies reported data on free-end saddles. Of the 13 studies associated with bilateral free-end saddle dentures, 9 studies showed a positive effect on masticatory efficiency. Various factors were found to have an impact on the MP of RPDs., Conclusions: Subjective evaluation displays higher positive impact of RPDs in MP than objective evaluation. Assessment of patients' perspectives is important in clinical decision-making. Multiple factors affect the MP with RPD treatment.

This preliminary study evaluated the adjunctive supporting role of diverse implant positions on stress distribution in a Class I removable partial denture (RPD) design. Nine three-dimensional finite element models were prepared to simulate mandibular RPD designs with three different loading conditions applied. Implant supported designs demonstrated lower stress value concentrations and mucosal displacement.

Purpose: The aim of this study was to determine the influence of occlusal support length (OSL) of free-end removable partial dentures (RPDs) on masticatory function., Materials and Methods: Twenty-three subjects (mean age: 55.2 ± 8.4 years) who were edentulous in the maxilla and classified as Kennedy Class I in the mandible were selected. Subjects received new maxillary complete dentures and mandibular RPDs. Five OSL conditions were determined by RPD artificial tooth wear: full occlusal support (L1, control), OSL to first molar (L2), OSL to second premolar (L3), OSL to first premolar (L4), and absence of occlusal support (L5). Masticatory performance and efficiency were evaluated using the sieve method. Chewing rate was defined as the number of masticatory cycles per minute. Bolus selection opportunities and bolus breakage function were evaluated using the one-chew method. Qualitative and quantitative measurements of masticatory cycle patterns were recorded kinesiographically. Data were analyzed using repeated-measures analysis of variance and Friedman and Fisher exact tests (α = .05)., Results: Masticatory performance and efficiency decreased (P < .05) from L1 (5.46 ± 0.64 mm and 51.21% ± 19.44%, respectively) to L5 (6.24 ± 0.44 mm and 24.50% ± 15.98%, respectively). Chewing rate was higher for L4 than L1 (P < .05). Bolus selection chances and bolus breakage function decreased as OSL was reduced (P < .05); however, there were no differences in masticatory cycle pattern among the OSL conditions (P > .05)., Conclusion: Reduction of OSL altered masticatory function, thereby decreasing masticatory performance and efficiency resulting from a lower capacity to select and break down food.

Mastication was evaluated in subjects presenting extremely shortened dental arches (ESDAs) rehabilitated with mandibular free-end removable partial dentures (RPDs). Subjects were divided into four groups (n = 10): those with a complete dentition, those with ESDAs, and those with ESDAs who were rehabilitated with an RPD, who were evaluated both with and without their prostheses. Mastication was measured through masticatory performance, time, and ability. RPD wearers showed higher masticatory performance (P < .01) and ability (P < .001) and lower masticatory time (P < .001) than when not wearing their prostheses as well as ESDA subjects who had not received RPD therapy. Those with a complete dentition showed the best results (P < .001). It can be suggested that RPDs improve mastication in ESDA subjects but without achieving normal mastication levels.

Purpose: Eichner Indices (A, B, and C), especially the Eichner subgroups (A1-A3, B1-B4, C1-C3), have not been validated in relation to oral functions. The purpose of this study was to investigate the association of posterior occlusal contact loss with occlusal force and masticatory performance in subjects who had a normal dentition or partially edentulous arches restored with removable prostheses., Materials and Methods: The study sample consisted of 1,288 independently living patients over the age of 60 years. Subjects were grouped into 10 subgroups by posterior occlusal contacts according to the Eichner Index. Bilateral maximum occlusal force in the intercuspal position was measured using pressure-sensitive sheets. Masticatory performance was determined by the concentration of dissolved glucose obtained from comminuted gummy jellies., Results: Occlusal force and masticatory performance were significantly associated with posterior occlusal contacts. Occlusal force measured in subgroups A2 to B2 and B3 to C3 did not differ statistically, although overall occlusal force decreased significantly as the loss of occlusal contacts increased. Similarly, masticatory performance was reduced with decreasing occlusal contact, although the decline was more gradual. Masticatory performance among subgroups A1 to B1, A3 to B2, B2 to B3, B4 to C2, and C1 to C3 did not differ significantly., Conclusions: The Eichner Index subgroups were significantly associated with reduced oral functions, even if the teeth were restored with removable prostheses. Preservation of occlusal contacts of the bilateral (B2) and unilateral (B3) premolars was critical for occlusal force and masticatory performance, respectively.

Purpose: The aim of this study was to compare the masticatory performance, maximum occlusal force, and occlusal contact area of subjects with bilaterally missing molars, treated either with the shortened dental arch (SDA) concept or with distal extension removable partial dentures (RPDs), during a 1-year follow-up., Materials and Methods: This study included three groups of 10 subjects each, in which SDA and RPD groups displayed bilateral molar loss in the mandible. Subjects with complete natural dentition (CD) served as the control group. Masticatory performance was evaluated by the multiple sieve method. Standard cubes (edge length: 8 mm, 0.9 g) shaped from a high viscosity polysiloxane molding material (Zetaplus, Zhermack) were used as the test food. Maximum occlusal force (N) and occlusal contact area (mm2) were evaluated using dental prescale films., Results: No statistically significant differences regarding masticatory performance between the groups or evaluation periods were demonstrated. In the RPD group, masticatory performance with and without prostheses showed no significant differences. SDA patients showed significantly lower contact area and occlusal force than both the CD and RPD groups (P < .05)., Conclusion: SDA can be an alternative to distal extension RPDs with respect to masticatory performance in subjects with bilaterally missing molars in one dental arch, despite remarkable reductions in maximum occlusal force and occlusal contact area.

Chewing ability and dental status were assessed in 2 Swedish counties via questionnaires sent in 1992 and 2002 to all subjects born in 1942. Those who answered both questionnaires-at ages 50 and 60-were included in the study (n = 5,008). The proportion of those who reported chewing ability as very good decreased from 75% to 66% during the 10-year follow-up. Approximately 80% of complete denture wearers considered their chewing ability to be good. Chewing ability was reported to be worse at age 60 than at age 50, although there was only a minor impairment in dental status.

Purpose: The purpose of this study was to investigate the relationship between self-assessed satisfaction with mastication and food acceptability and masticatory performance in a large sample of older adults with various occlusal statuses., Materials and Methods: The subjects were 708 community-dwelling, independently living elderly persons (351 men and 357 women) with a mean age of 66.0 (SD: 4.2) years. Satisfaction with masticatory function and food acceptability (apples, grilled beef, and hard rice crackers) were evaluated using questionnaires. Masticatory performance was determined using test gummy jellies developed for measuring masticatory performance. Subjects were grouped into 3 categories by posterior occlusal contacts according to the Eichner Index. The Kruskal-Wallis test and a multiple logistic regression analysis for dissatisfaction with masticatory function were conducted., Results: Overall, posterior occlusal contacts, food acceptability, and masticatory performance were associated with satisfaction with masticatory function when evaluated with bivariate analysis. Multiple logistic regression analysis showed that the number of foods that could be eaten without difficulty was the most important explanatory variable for dissatisfaction with masticatory function (P < .01). In contrast, objective masticatory performance was not significantly associated with dissatisfaction with masticatory function (P = .057) after controlling for posterior occlusal contacts and food acceptance., Conclusions: The subjective masticatory function was associated not only with objective masticatory performance, but also with an individual's posterior occlusal contacts.

Purpose: Patients' oral health needs are estimated through dialogue and professional assessment. The concepts of need and demand are vital to studies of dental care and oral health. Need does not always lead to demand for treatment or to utilization, depending on the gatekeeping processes between need and demand and between demand and utilization. Demand must be accepted with the understanding that there is no objective need and that demand depends on the patient's opinion. In accordance with this, the need for prosthodontic treatment is highly individual and is not automatically related to oral health status, making need and demand difficult to measure in that respect. Therefore, sociodental factors should be included and evaluated in studies of need and demand for utilization of prosthodontic care., Materials and Methods: This theoretical and analytic paper focuses on the gatekeeping processes between need and demand and between demand and utilization of prosthodontic care., Results: The concept of gatekeeping refers to the social and psychologic processes that transform need into demand and demand into utilization. It implies that they are complex processes that can render great differences between demand and actual utilization., Conclusion: It is not possible to estimate a patient's needs for prosthodontic care, since there is no objective need. Demand and utilization are factors that play an important role in the gatekeeping process. These factors are dependent on the patient's opinion, which is influenced by numerous factors.

Purpose: This study aimed to clarify the relationship between oral function and Body Mass Index (BMI) using data from independently living, relatively healthy older people. The hypothesis was that oral function is more important than dental status for healthy body weight., Materials and Methods: The subjects were community-dwelling, independently living elderly people over 60 years of age (N = 807, 408 men and 399 women). An oral health examination, an oral and general health interview, and measurement of oral function, such as masticatory performance and occlusal force, were carried out. BMI (kg/m2) was used to measure body fat. A multiple logistic regression analysis was used for 2 outcome variables of underweight and overweight., Results: Overall, 70.1% of the subjects were in the normal category of BMI (20 to 25), 13.4% were in the underweight category (< 20), and 16.5% were in the overweight category (> 25). Neither occlusal force nor masticatory performance was significantly correlated with BMI. However, when the lowest 20% of occlusal force and masticatory performance values were used as explanatory variables, multiple logistic regression analyses showed that being underweight was significantly associated with having lower masticatory performance (odds ratio = 2.0, P= .015). In addition, being overweight was significantly associated with lower occlusal force (odds ratio = 1.8, P = .013). There was no statistical difference in the underweight or overweight proportions as a function of either number of teeth or type of dentition., Conclusion: Based on the results of this study, occlusal force and masticatory performance, rather than number of teeth or type of dentition, may play an important role in maintaining a normal BMI in independently living older Japanese people.

Purpose: Eating, which includes chewing and swallowing, is an oral function that influences quality of life. Though the swallowing ability of maxillectomy patients was reported in our previous study, the chewing function has not been fully reported to date. Thus, the purpose of this study was to evaluate the chewing function of obturator prosthesis wearers by measurement of masticatory performance and occlusal force. The relationship of these 2 measurements was also investigated., Materials and Methods: Twenty maxillofacial obturator prosthesis wearers undergoing periodic checkup at the maxillofacial rehabilitation clinic in Kyushu University Hospital were recruited for this study. Additionally, 20 young, healthy individuals were recruited as controls. Data on masticatory performance, which was measured by a sieve method using hydrocolloid material, and maximum occlusal force, which was measured by the Dental Prescale System (Fuji Film), were obtained for each participant., Results: The mean of masticatory performance was 2.6 (SD 1.2) on a 1.40-mm mesh. There was no significant difference in masticatory performance between the patient group and the controls. The mean maximum occlusal force of the patient group was 625.9 N (SD 299.1 N), which was significantly lower than that of the control group. There was no significant correlation between masticatory performance and maximum occlusal force for the patient group in this study (P = .3726)., Conclusion: Masticatory performance of obturator prosthesis wearers with dentate or partially edentulous maxillae was not different from that of young, healthy individuals, though maximum occlusal force of these patients was lower than that of controls.

Purpose: The purpose of the study was to determine the changes in bone mineral density of the mandible in complete and removable free-end saddle denture wearers over a 6-month period., Materials and Methods: Twenty removable partial denture patients and 20 complete denture wearers participated. Two dental panoramic radiographs were taken from each patient, the first prior to denture delivery and the second after 6 months of denture wearing. Bone mineral density measurements were performed on panoramic radiographs with a five-step copper stepwedge attached to each film cassette. Bone mineral density values of the measured regions of interest were expressed in equivalents of the stepwedge thickness (mm)., Results: The results revealed minor changes in bone mineral density values of the examined regions in the 6-month period. Under the distal end of complete denture saddles, the bone mineral density values decreased, whereas the values under the distal end of removable partial dentures increased. However, the difference between the first and second measurements was not significant. In each of the examined groups, the bone mineral density values at the gonion increased significantly by approximately 20%. This was attributed to the increased strain forces of the masseter muscle at the gonion after denture delivery., Conclusion: Significant increase of bone mineral density values was registered 2 mm above the gonion in both complete and removable partial denture wearers. Age and gender were not related to the bone mineral density changes over a 6-month period.

Purpose: The aim of this study was to investigate the changes in interocclusal distance during the pronunciation of /m/ and /s/ sounds in the Portuguese language, in partially edentulous patients before and after insertion of new dentures., Materials and Methods: Subjects were divided into a control group consisting of 18 completely dentate patients and an experimental group consisting of 18 patients who were edentulous in the maxilla and classified as Kennedy Class I in the mandible. The experimental group had new dentures placed and the occlusal vertical dimension corrected. A magnetic jaw-tracking device measured the interocclusal distance during pronunciation of the /m/ and /s/ phonemes. Interocclusal distance evaluations were carried out in a single session for the control group. In the experimental group, the measurements were carried out before insertion of new dentures; immediately after insertion; and after 6 and 24 hours; 2 days; 1 and 2 weeks; 1, 2, 3, and 6 months; and 1 year., Results: Comparison between groups revealed significant difference in interocclusal distance for the /m/ sound both before and after insertion of dentures up to 2 months. For the /s/ phoneme, there was no difference between the groups before prosthesis insertion, or after 3, 6, and 12 months of prosthesis use. There were significant differences for the /m/ sound only at 6 and 12 months after new denture insertion, and for the /s/ sound at all periods evaluated., Conclusion: Insertion of new dentures, with the vertical dimension corrected, changes the interocclusal distance of speech during phonation of /m/ and /s/ sounds.

Purpose: The aim of this study was to verify the hypothesis that shortened dental arches constitute a risk to occlusal stability., Materials and Methods: Using cluster samples, 725 subjects with shortened dental arches comprising intact anterior regions and zero to eight occluding pairs of posterior teeth and 125 subjects with complete dental arches were selected. Subjects with shortened dental arches were classified into eight categories according to arch length and symmetry. Parameters for occlusal stability were interdental spacing, occlusal tooth wear, occlusal contact of incisors in intercuspal position, and vertical and horizontal overlap. Additionally, tooth mobility and overeruption of unopposed teeth were assessed. Influence of independent variables (dental arch category, age, gender, and residence) on the parameters for occlusal stability was assessed by one-way ANOVA and Tukey's multiple range tests., Results: Extreme shortened dental arches (zero to two pairs of occluding premolars) had significantly more interdental spacing, occlusal contact of incisors, and vertical overlap compared to complete dental arches. Occlusal wear and prevalence of mobile teeth were highest in these categories. The category with three to four occluding premolars had significantly more interdental spacing and, for the older age group, more anterior teeth in occlusal contact compared to complete dental arches. Age was consistently associated with increased changes in occlusal integrity., Conclusion: Signs of increased risk to occlusal stability seemed to occur in extreme shortened dental arches, whereas no such evidence was found for intermediate categories of shortened dental arches.

Purpose: Forceful clenching in the intercuspal position has the potential to cause significant mandibular displacement. Such a displacement can be expected to be exaggerated in patients without molar support. The appropriate clenching level for intercuspal position registration or evaluation in these patients has never been clarified. The aim of this study was to clarify the effect of clenching level and absence of posterior occlusal support on mandibular displacement., Materials and Methods: Thirteen women with a unilateral edentulous area posterior to the first premolar were enrolled in this study. They were asked to perform intercuspal clenching at various occlusal force levels, and 3-D mandibular displacements were measured by an optoelectronic method. The effects of "clenching force level" and "side of molar tooth loss" on the displacements of the condylar and second molar points were analyzed., Results: The mandible was elevated without substantial horizontal displacements during each clenching task. The effect of clenching level on vertical mandibular displacement was significant, with a clenching level > or = 50% of maximal voluntary contraction causing significantly greater elevations (P < .05). Clenching > or = 50% of maximal voluntary contraction caused consistent tipping of the mandible, with greater elevation on the edentulous side (P < .05)., Conclusion: The clenching level should not surpass 50% of maximal voluntary contraction for registration or evaluation of intercuspal position in Kennedy Class II patients.

Purpose: There has been a general belief that permanent teeth without antagonists overerupt, creating, after some time, considerable clinical problems. However, very few studies in the literature support this statement. The purpose of this investigation was to examine the position of molars that had been unopposed for a long period and to test the hypothesis that overeruption does affect every tooth without an antagonist., Materials and Methods: Fifty-three individuals were examined clinically, and dental casts were taken to evaluate the position of unopposed molars. There were 84 molars (61 in the maxilla and 23 in the mandible) with a documented period of at least 10 years without antagonists. Among these teeth, 25 molars had neither an antagonist nor a mesially adjacent tooth. A qualitative method was used to evaluate the position of the molars in the vertical direction: (1) teeth with no sign of overeruption, (2) teeth with slight overeruption (< 2 mm), and (3) teeth with moderate to severe overeruption (> or = 2 mm)., Results: Of the 84 molars examined, 15 teeth (18%) revealed no signs of overeruption, 49 teeth (58%) displayed overeruption of less than 2 mm, and 20 teeth (24%) showed moderate to severe overeruption. Individuals with molars that had lost their antagonists in adult age had a lower risk for overeruption than the other subjects examined. The existence of adjacent teeth was important for the position of the unopposed molar in a mesiodistal or buccolingual direction. Molar rotation was more frequent in the maxilla, whereas tipping was more common in the mandible., Conclusion: It is concluded that not all molars without antagonists overerupt, not even in a long-term perspective.