Effect of prosthetic restoration on masticatory function in patients with shortened dental arches: a multicentre study

'Thermo-mechanical behavior of alternative material combinations for full-arch implant-supported hybrid prostheses with short cantilevers'

OBJECTIVES

To compare the fracture resistance (FR) of three combinations of materials for full-arch maxillary implant-supported hybrid prostheses (HPs) with short cantilevers (≤ 10 mm).

METHODS

Maxillary HPs were fabricated and classified as follows (n = 5 each): Group-1 (CC-A, control): acrylic-resin-veneered Co-Cr frameworks; Group-2 (CF-A): acrylic-resin-veneered carbon-fiber mesostructures; and Group-3 (CF-R): composite-resin-veneered carbon-fiber frames. Specimens were thermal-cycled (5,000 cycles; 5 °C-55 °C; dwell time: 30 s). Vertical loads were applied until failure, first at the 10-mm-long cantilever (LC), and, afterwards, at the anterior region (AR), using a universal testing machine (crosshead speed: 0.05 mm/s). The fracture pattern was assessed by stereomicroscope and SEM. The one-way ANOVA, the Bonferroni, and the independent samples t tests, were run (α= 0.05).

RESULTS

At LC, CF-A, and CC-A samples exhibited the highest FR values (p< 0.001), showing no differences to each other. At AR, CC-A specimens recorded the highest FR, followed by CF-A samples (p< 0.001). CF-R HPs displayed the lowest FR at both locations (p< 0.001). The only group with differences between the tested sites was the CC-A, the AR being more resistant (p< 0.001). Most CC-A and CF-A HPs failed cohesively. CF-R prostheses mainly failed adhesively.

CONCLUSIONS

Maxillary HPs with short cantilevers (≤ 10 mm) made of Co-Cr or carbon-fiber veneered with acrylic resin demonstrated an adequate mechanical resistance (> 900 N).

CLINICAL SIGNIFICANCE

For maxillary HPs with cantilevers up to 10 mm, acrylic-veneered carbon- fiber mesostructures may be recommended, whereas coating carbon-fiber frames with composite resin seems not suitable.

Oral function of implant-assisted removable partial dentures with magnetic attachments using short implants: A prospective study

OBJECTIVES

This prospective study aimed to compare the oral functions of removable partial dentures (RPDs) with those of implant-assisted removable partial dentures (IARPDs) with short implants and magnetic attachments in patients with mandibular Kennedy class I and II.

MATERIAL AND METHODS

Thirty participants with mandibular Kennedy class I or II and at least three distal missing teeth were recruited. Oral functions, including mixing ability, comminuting ability, maximum bite force, and occlusal contact area, were assessed for RPDs (stage 0), IARPDs with healing caps (stage 1), and IARPDs with magnetic attachments (stage 2). The implants were loaded with occlusal force in stages 1 and 2. Finally, the data of the 27 participants who completed the evaluation at stage 2 were analyzed. The Wilcoxon signed-rank test with Bonferroni correction was used to assess the differences in the oral functions among the different stages.

RESULTS

The implant survival rate was 93.8%. There were significant differences in the comminuting ability and occlusal contact area between stages 0 and 2 (p < .001 and p = .036, respectively) and stages 1 and 2 (p = .003 and p = .015, respectively). Regarding the maximum bite force, there was a significant difference between stages 1 and 2 (p = .018). However, there was no significant difference in the mixing ability between the three stages.

CONCLUSIONS

Within the limitations of this study, it was concluded that IARPDs in the mandible with short implants and magnetic attachments may improve oral functions.

Regular Oral Health Management Improved Oral Function of Outpatients with Oral Hypofunction in Dental Hospital: A Longitudinal Study

This longitudinal study aimed to clarify the impact of regular oral health management for oral hypofunction on the oral function of older dental outpatients. The 68 participants enrolled in this study were older dental outpatients (mean age 78.5 ± 8.1 years). According to the number of declined oral examinations after the first exam, participants were assigned to the oral hypofunction group (Hypo group, ≥3), receiving regular oral health management with a leaflet at the dental clinic, or the pre-oral hypofunction group (Pre-hypo group, ≤2), which served as a control. At the second oral examination, after approximately 6 months to 1 year, the Hypo group showed significant improvement in the tongue-lip motor function (Oral diadochokinesis, ODK) /pa/, /ta/, and masticatory function, while the Pre-hypo group showed significant worsening in oral hygiene and oral wetness. Temporal changes in ODK /pa/, /ta/, and the number of declined examination items were significantly different between the groups. Multiple analysis revealed that the number of improved oral examination items were associated with presence of regular oral health management after adjusting for age, sex, number of visits, measuring period, and dental treatment. Regular comprehensive oral health management for oral hypofunction improves and maintains oral function among older dental outpatients.

Impact of oral health guidance on the tongue-lip motor function of outpatients at a dental hospital

Objective

To clarify the effect of oral health guidance on tongue‐lip motor function in the outpatients visiting the Showa University Dental Hospital (Tokyo, Japan).

Background

The management of the oral function of older people visiting a dental hospital is important. Previous studies have revealed that tongue‐lip motor function is easy to improve. However, the impact of oral health guidance on tongue‐lip motor function in the outpatients of dental hospital requires further elucidation.

Materials and Methods

The participants (n = 35) included patients who were diagnosed with low tongue‐lip motor function on evaluation by oral diadochokinesis (ODK) at the outpatient clinic. They underwent a second examination approximately 6‐12 months later. Their demographic characteristics were recorded. Oral health guidance was provided through an educational leaflet on oral hypofunction when the participants visited the clinic. It included content on tongue twisters, voice training and a range of movement and muscle training of the tongue and lip.

Results

Following oral health guidance on tongue‐lip motor function, the ODK values changed from 5.6 at the first examination to 6.0 at the second for /pa/, from 5.6 to 5.8 for /ta/ and from 5.2 to 5.4 for /ka/. This improvement was not significantly associated with age, sex, measurement period or number of visits.

Conclusion

The findings of this longitudinal study suggested that oral health guidance using an oral hypofunction educational leaflet may be effective in improving the tongue‐lip motor function of outpatients who had low tongue‐lip motor function, regardless of the measurement period or the number of visits to the dental hospital.

Interrelationships among whole-body skeletal muscle mass, masseter muscle mass, oral function, and dentition status in older Japanese adults

Background

Generalized loss of skeletal muscle mass (SMM) may modulate or otherwise affect the loss of masseter muscle mass and be responsible for low masseter muscle performance and strength (i.e., low oral function). Moreover, dentition status can affect oral function independent of the muscle state. This cross-sectional study aimed to simultaneously investigate the relationships among whole-body SMM, masseter muscle mass, oral function (masseter muscle performance and strength), and dentition status in 1349 Japanese adults (mean age = 73.6 years).

Methods

We determined the estimated masseter muscle mass (e-MMM) based on morphological measurements of the masseter muscle. Masseter muscle performance was assessed via masticatory performance evaluation scores using gum, and strength was assessed as the maximal occlusal force. Dentition status was assessed as the number of functional teeth. SMM was measured by bioelectrical impedance analysis. Structural equation modeling stratified by sex was employed to investigate associations among SMM, e-MMM, gum score, occlusal force, and number of functional teeth.

Results

The direct path from SMM to e-MMM was statistically significant, as was the direct path from e-MMM to oral function (gum score and maximum occlusal force) for both sexes. We additionally confirmed that SMM indirectly affected gum score and maximum occlusal force via e-MMM (men; standardized coefficient [95% CI] = 3.64 [1.31 to 5.96] for maximum occlusal force and 0.01 [0.01 to 0.02] for gum score, women; 2.01 [0.38 to 3.81] for maximum occlusal force and 0.01 [0.002 to 0.01] for gum score). The number of functional teeth had direct effects on e-MMM, gum score, and maximum occlusal force.

Conclusions

Low SMM was significantly indirectly associated with poor oral function through a low masseter muscle mass, and dentition status was independently associated with oral function.

The impacts of prosthetic interventions on mastication predominance in Kennedy Class Ⅱ patients

Purpose The purpose of this study was to investigate the effects of prosthetic interventions in patients with Kennedy Class Ⅱ (unilateral missing posterior teeth) on mastication predominance.Methods The subjects comprised patients with Kennedy Class II and healthy dentate volunteers (HD group). The subjects were asked to freely chew the test foods (chewing gum, beef jerky, and peanuts). Electromyographic activity of the bilateral masseter muscles was recorded twice (before and after prosthetic intervention). The chewing side (right or left) was judged by the level of the root mean square electromyographic amplitude. Mastication predominance was assessed using the mastication predominance index (MPI; range 0-100%). Each patient was restored with a removable partial denture (RPD) or an implant-supported fixed prosthesis (IFP). The effects of prosthetic interventions were statistically evaluated by the differences between MPI before and after prosthetic interventions (pre-MPI and post-MPI , respectively).Results There was a significant difference between pre-MPI of patients with Kennedy Class II and MPI of the HD group (HD-MPI) for all test foods (P < 0.0001). Statistical analysis also demonstrated a significant difference between pre-MPI and post-MPI measured with each of the three food items in both the RPD and IFP groups (P < 0.0001). Multiple comparisons revealed that post-MPI in the IFP group, but not in the RPD group, was statistically comparable with HD-MPI, although there were no significant differences among the three groups when MPIs were calculated using peanuts.Conclusions Prosthetic interventions improved mastication predominance in patients with Kennedy Class Ⅱ patients. Depending on the food type, IFP might contribute to better improvement of mastication predominance than RPD depending on food.

A new masticatory performance scale to integrate food biting, comminution and mixing ability in removable partial denture wearers

BACKGROUND

The existing masticatory performance (MP) tests cannot comprehensively evaluate objective masticatory function.

OBJECTIVES

We aimed to examine the construct validity and responsiveness and determine the clinically minimum important difference (MID) and related factors of a newly developed MP scale to integrate food biting, comminution and mixing ability in patients with removable partial dentures (RPDs).

METHODS

Masticatory performance tests using gummy jelly, peanuts and colour-changeable gum were performed before and 3 months after RPD treatment in 248 partially dentate patients. A 10-point ordinal subscale was created for each MP test based on the distributions of MP values, and the three subscales were integrated into a single scale (iMP scale). We analysed the correlations between MP values and iMP scores and determined the effect size for RPD treatments and the MID on the basis of patient perception of chewing ability.

RESULTS

iMP scores exhibited moderate correlations with the three MP values (|ρ| = 0.73-0.79, p < .001) and with the change scores (|ρ| =0.61-0.64, p < .001). The mean iMP score significantly increased after RPD treatment (p < .001), and the effect size was 0.35. Of the 248 patients, 55 (22%) reported a slight improvement in chewing ability with a mean iMP score change of 2.1 points. Sex and the number of missing teeth were significantly associated with iMP scores (p < .05).

CONCLUSIONS

The iMP scale comprehensively evaluated objective masticatory function, including food biting, comminution and mixing ability in RPD wearers, and an increase of two points on the iMP scale was considered to be the MID in RPD treatments.

Responsiveness of methods to evaluate objective masticatory function in removable partial denture treatments

PURPOSE

The aim of this study was to examine the responsiveness of chewing tests after removable partial denture (RPD) treatment in this prospective cohort study.

METHODS

Pre- and post-RPD treatment, objective masticatory function was evaluated in 248 patients via chewing tests involving peanuts, a gummy jelly, and a color-changeable gum. A statistical comparison was performed between the pre- and post-treatment scores, and the standardized response mean (SRM) was determined as the treatment effect size (ES).

RESULTS

After RPD treatment, the median particle size in the sieving method using peanuts significantly decreased, and the glucose concentration in the gummy jelly method significantly increased (P < 0.001). The ESs of the sieving and gummy jelly methods were larger (|SRM| = 0.3-0.4) than that of the gum method (|SRM| = 0.1). In the subgroup analysis, the sieving and gummy jelly methods resulted in a broader effective range (|SRM| ≥ 0.3) than the gum method. In patients without pre-treatment dentures, the ES was medium in the sieving method (|SRM| = 0.6) and weak in the gummy jelly and gum methods (|SRM| = 0.3-0.4). The pre-treatment level of masticatory function was significantly correlated with ES (ρ = 0.93, P < 0.001).

CONCLUSIONS

These results suggest that the sieving and gummy jelly methods are more responsive than the gum method for RPD treatment and that the pre-treatment scores affect the responsiveness.

Oral frailty and gait performance in community-dwelling older adults: findings from the Takashimadaira study

PURPOSE

This cross-sectional study compared gait performance between community-dwelling older adults with and without accumulated deficits in oral health, defined as oral frailty.

METHODS

A total of 1,082 individuals (439 men and 643 women; mean age, 77.1 years) from the Takashimadaira study were included in the current analysis. Based on a multifaceted oral health assessment, oral frailty was defined as having three or more of the following six components: (i) fewer teeth, (ii) low masticatory performance, (iii) low articulatory oral motor skills, (iv) low tongue pressure, (v) difficulties in eating, and (vi) swallowing. Eight gait parameters were assessed using an electronic walkway. Gait characteristics comparison between groups with and without oral frailty was performed using multiple linear regression models. Models were adjusted for age, sex, educational status, income, smoking, drinking, physical activity level, height, body mass index, comorbidities, and the presence of chronic pain.

RESULTS

Oral frailty was observed in 227 (21.0%) participants. After adjusting for potential confounders, the participants with oral frailty had slower gait speed, shorter stride and step length, wider step width, and longer double support duration as well as higher variability of stride length and step length.

CONCLUSIONS

Oral frailty was associated with poor gait performance among community-dwelling older adults.

Responsiveness of methods to evaluate chewing ability after removable partial denture treatments

BACKGROUND

The ability of an instrument to detect a clinically important change in patient-reported outcomes following prosthetic treatment is critical for its use in clinical practice and research settings.

OBJECTIVES

This study aimed to examine the responsiveness of instruments in evaluating patient perception of chewing ability after removable partial denture (RPD) treatment in a prospective cohort.

METHODS

A single 100-mm visual analogue scale (VAS), 20-item food intake questionnaire (FIQ) and 6-point chewing difficulty scale (CDS) were administered to 248 partially edentulous patients to evaluate chewing ability pre- and post-RPD treatment. We conducted a statistical comparison between the pre- and post-treatment scores and determined the effect size (r) of RPD treatment for the instruments.

RESULTS

A significant improvement in chewing ability after RPD treatment was identified by VAS and CDS (P < .05), but not by FIQ (P = .16), which identified an improvement after controlling for sex, age, the number of missing teeth and presence/absence of existing removable dentures. The effect size was medium for VAS (r = .54), weak for CDS (r = .14-.17) and absent for FIQ (r = -.09). The increase in r was significantly associated with impaired chewing ability before treatment (ρ = -0.87, P < .001).

CONCLUSIONS

These results suggest that the 100-mm VAS, followed by CDS, is the most responsive instrument to detect an improvement in chewing ability after RPD treatment. Pre-treatment impairment of chewing ability was associated with better responsiveness of the instruments.

Masticatory ability in older individuals: A qualitative interview study

Aim

To explore older individuals’ experienced masticatory ability and the impact of masticatory ability in daily life.

Material and methods

This study applied an open‐ended exploratory approach using inductive reasoning. The design was inspired by the qualitative method grounded theory. The final sample consisted of twelve older participants. Seven were men, and five were women. The interviews were audio‐recorded and transcribed verbatim. The interviewer successively read the transcribed data and analysed the material in cooperation with the authors.

Results

Three categories developed from the data; Deteriorating oral health and functional loss, Eating habits, Prosthetic rehabilitation and function. A core category named Adaptation emerged. Adaptation describes how individuals successfully could adapt to a decreased function and in spite of this develop a positive view of their masticatory ability.

Discussion

The participants described an experience of gradually deteriorating oral function that had affected their masticatory ability. By adapting to this functional degradation, some of the participants overcame the functional deficiencies. Most participants perceived their masticatory ability to be good, even though their ability to process some food types was described as inadequate.

Conclusion

The participants had experienced deteriorating oral health and function throughout life, and they overcame this through adaptation by adjusting their eating habits. Even though prosthetic treatment might be considered successful by the participant, this does not necessarily improve dietary habits. Future research should therefore focus on how dental treatment can be combined with other interventions, such as dietary counselling and physiotherapy to recover physiological function.

Factors Influencing Changes in Masticatory Performance as a Result of Wearing Removable Partial Dentures in Patients with Partially Edentulous Arches

PURPOSE

To measure masticatory performance (MP) in partially edentulous patients when wearing removable partial dentures (RPDs) versus when not wearing RPDs, and to identify factors that could enable clinical evaluations related to differences in MP.

MATERIALS AND METHODS

This study consisted of 87 partially edentulous patients (57 females, 30 males; mean age, 69.41 ± 8.85 years) categorized as Eichner classification B who habitually wore RPDs. MP was evaluated while wearing versus while not wearing RPDs using test gummy jellies. The participants were categorized into four groups by the presence of occlusal contacts in one to three of the molar and premolar regions (occlusal support), or in the anterior region only, according to the Eichner index (B1-B4). The participants were also categorized according to the jaw on which the RPDs were worn and the Kennedy classification, and evaluated in regard to changes in MP resulting from wearing RPDs. Additionally, the rate of change in MP (MP-rv) was calculated for each participant using MP when not wearing RPDs as a reference, and factors affecting MP-rv were evaluated using single or multiple regression analysis and the Kruskal-Wallis test with multiple comparisons.

RESULTS

Significant increases in MP-rv were observed for all participants and for those with occlusal support in two (p = 0.006) and three regions (p = 0.019); however, no significant differences were observed when wearing and not wearing RPDs in participants with (p = 0.090) and those without occlusal support in one region (p = 0.474). With respect to the jaw on which the RPDs were worn, only maxillary or both maxillary/mandibular RPDs tended to have higher MP-rvs than did only mandibular jaws. The results of the multiple regression analysis showed that Kennedy Class I edentulous arches were a factor in increasing MP-rv (standard partial regression coefficient = 0.46, p < 0.05).

CONCLUSION

According to the results of this study, among various factors on the degree of improvement in masticatory performance by wearing RPDs, bilateral missing posterior teeth might be a predictor for achieving clinical improvement.

Chewing Performance Calculator: An interactive clinical method for quantifying masticatory performance

STATEMENT OF PROBLEM

There is a need to quantitatively differentiate between impaired and normal mastication by using straightforward and reliable methods because currently available methods are expensive, complex, and time-consuming.

PURPOSE

The purpose of this clinical study was to assess the reliability, validity, and clinical utility of a new Web-based software program designed to calculate masticatory performance, the Chewing Performance Calculator (CPC) measuring masticatory performance (MP), by analyzing the area of mixed bicolored chewing gum.

MATERIAL AND METHODS

One hundred and ten participants were consecutively recruited from the School of Dentistry of the University of Salamanca. MP was determined by using 2-colored chewing gum that was masticated for a total of 20 strokes. The masticated gum was then flattened between 2 transparent glass tiles, generating a 1-mm-thick specimen that was scanned to calculate the percentage of area where the 2 colors were mixed. The area was calculated by using a photo-editing software program as described by Schimmel et al (standard method). In addition, all the images were analyzed by using the CPC Web application, which took as input the image of the masticated bolus enclosed in a custom plastic platen that allowed 3 parts of the image to be selected interactively: the platen, the bolus background, and the mixed color fraction of the bolus. The application then computed MP as a percentage. Additionally, an oral examination was carried out to record the number of occlusal units. These data were used to assess the validity of CPC by using the Pearson correlation coefficient. Construct validity was assessed by using ANOVA by comparing the MP scores obtained for masticated gums, classified upon inspection as being poorly, moderately, or highly mixed. The time spent evaluating the specimens with GSM and CPC methods was also recorded and used to indicate the usefulness of the procedure.

RESULTS

The MP was found to range between 5.2% and 100% (95% CI: 80.8-88.8) with the GSM and between 9.2% and 96.4% (95% CI: 60.0-67.6) with the CPC. The time needed to calculate MP by using the GSM was significantly higher (235.2 versus 260.5 seconds) than that with the CPC (42.3 to 48.6 seconds). Both methods were significantly intercorrelated (r=0.65; P<.001) and correlated with the number of occlusal units (r=0.54 for CPC and r=0.40 for GSM). The correlation coefficient of MP calculated by using CPC (r=0.54; P<.001) was greater than that calculated by using GSM (r=0.40; P<.001). Moreover, both methods showed adequate construct validity because the values calculated for MP significantly increased as the mixing of the masticated gums also increased, subjectively classified as poor, moderate, and high.

CONCLUSIONS

The CPC software program allowed MP to be determined in a valid and easy-to-use manner by using 2-colored chewing gum.

Do implant-supported fixed partial prostheses improve masticatory performance in patients with unilateral posterior missing teeth?

OBJECTIVES

The purpose of this study was to determine the improvement in masticatory performance and satisfaction with chewing ability in partially edentulous patients after treatment with an implant-supported fixed partial prosthesis (ISFPP).

MATERIAL AND METHODS

This prospective study included 30 patients (mean age 59 years; 17 women) with unilateral posterior missing teeth treated with one-, two- or three-unit ISFPPs and 10 healthy individuals (mean age 36 years; 8 women) with complete natural dentition to establish the normal levels of mastication. Three variables were determined at baseline and at 3-months' follow-up in all participants: masticatory performance according to the median particle size (MPS) during freestyle mastication and unilateral mastication on each side, and satisfaction with chewing ability using a visual analog scale. Paired samples t test and Kruskal-Wallis test were used for intra-group and inter-group comparisons.

RESULTS

The MPS following freestyle mastication decreased significantly at 3 months in both groups. Significant reductions of 21%, 30%, and 42% in the MPS were obtained from unilateral mastication on the treated side after treatment with 1, 2, or 3 restorative units, respectively. Three months after ISFPP, satisfaction with chewing ability improved by 40% in the treatment group.

CONCLUSIONS

Freestyle masticatory performance may improve slightly within three months of treatment with an ISFPP and may be similar to that of subjects with complete natural dentition. Patients may obtain a 21%-38% improvement in unilateral mastication on the treated side and a 26%-54% improvement in satisfaction with chewing ability.

A systematic review and meta-analysis of the survival rate of implants placed in previously failed sites

The aim of this study was to conduct a systematic review and meta-analysis to assess the clinical outcomes of dental implants placed in previously early and late implant failed sites. An electronic literature search was conducted in several databases for articles published up to February 2018. Human clinical trials that received at least one implant in a previously failed site were included. Hence, the PICO question that was aimed to be addressed was: Do patients undergoing implant replacement (second and third attempts) in previous failed sites have survival rates similar to implants placed at first attempts? A random effects model was used to calculate survival weighted means and corresponding 95% Confidence Intervals (CI) among studies. Eleven studies of low to moderate methodological quality were included in this review. Implants placed in sites with history of one and two implant failures had a weighted survival rate (SR) of 88.7% (95%CI 81.7-93.3) and 67.1% (95%CI 51.1-79.9), respectively. Implants placed in sites with a previous early failure revealed a weighted SR of 91.8% (95%CI 85.1-95.6). First implants presented higher SR than implants placed in sites with one or two previous implant failures. In contrast, implants placed in sites with one and two implant failures had similar SR. Within its limitations, this review suggests that replacement implants have moderate SR. Larger prospective studies with well-defined criteria for early and late implant failure are necessary to confirm and expand on these results.