Comparison of Rehabilitating Missing Mandibular First Molars with Implant- or Tooth-Supported Prostheses Using Masticatory Efficiency and Patient Satisfaction Outcomes

Lip and tongue strength associated with chewing patterns in aging population

BACKGROUND

Improving chewing function of older adults increases the health-related quality of life. Few studies indicated the correlation between tongue, lip strength on masticatory performance in older people. The study aimed to investigate the association between lip, tongue strength on chewing pattern in aging population.

METHODS

The older adults had independent daily intake without assistance were enrolled. They had intact dentition and no periodontitis. To estimate the number of chewing strokes and chewing time by consuming a cornstarch cookie were used to represent chewing pattern. Lip and tongue pressure were evaluated with an Iowa Oral Performance Instrument. Linear regression analysis was used to analyze the lip and tongue pressure associated with the chewing time and strokes. Spearman's correlation analysis was utilized to evaluate the associations among chewing time and chewing strokes or lip and tongue pressure.

RESULTS

35 women and 35 men with an average age of 73.2 years were investigated. Tongue pressure was significantly related to the chewing time and the number of chewing strokes (p = 0.01 and 0.03). There was a close association between chewing time and the number of chewing strokes (p < 0.0001). The correlation between lip and tongue pressure was significant (p < 0.0001).

CONCLUSION

The tongue strength significantly related to chewing ability in aging population. Increasing the tongue strength greatly reduced the number of chewing strokes and chewing time. Good masticatory ability could increase the motor function of tongue; raising the tongue strength might be able to improve mastication in older adults.

Prospective evaluation of implants-supported, tooth-implant supported, and teeth-supported 3-unit posterior monolithic zirconia fixed restorations: Bite force and patient satisfaction

OBJECTIVES

This study aimed to evaluate the maximum bite force (MBF) and satisfaction of patients restored with implants, combined tooth-implants, and teeth-supported monolithic zirconia fixed dental prostheses (FDPs).

MATERIALS AND METHODS

Thirty partially edentulous patients in need of three units of FDPs in their mandibular posterior region were divided into three equal groups (n = 10) as follows: Group-1 patients received two implants for each at the second premolar and second molar regions, Group-2 patients received one implant for each at the second molar region, and Group-3 patients with missing lower first molar. All the restorations were constructed from monolithic zirconia. Patients were evaluated 1 week after placement of restorations (baseline) and then after 6, 12, and 24-month intervals for MBF using force transducer occlusal force meter and satisfaction (function, esthetic, and overall satisfaction) using a visual analog scale.

RESULTS

The mean MBF for Group 1 was higher than Group 2 (p = .044) but not that of Group 3 (p = .923). Additionally, Group 3 displayed a higher MBF than Group 2, although this difference was not statistically significant (p = .096). Concerning patient satisfaction, all study groups reported high levels of satisfaction across all satisfaction elements, and no significant differences were observed between the groups.

CONCLUSION

Within the limitations of this study, it can be concluded that Group 1 gives comparable anticipated treatment outcomes as Group 3 concerning biting force and patient satisfaction. However, Group 2 gives comparable satisfaction results with biting force value within the normal range; thus, it might be used as a treatment option in a specific situation.

Characteristics of Spatial Changes in Molars and Alveolar Bone Resorption among Patients with Loss of Mandibular First Molars: A CBCT-Based Morphometric Study

OBJECTIVES

To investigate the characteristics of spatial changes in molars and alveolar bone resorption among patients with loss of mandibular first molars.

METHODS

A total of 42 CBCT scans of patients with missing mandibular first molars (3 males, 33 females) and 42 CBCT scans of control subjects without loss of mandibular first molars (9 males, 27 females) were evaluated in this cross-sectional study. All images were standardized using the mandibular posterior tooth plane with Invivo software. The following indices regarding alveolar bone morphology were measured, including alveolar bone height, bone width, mesiodistal and buccolingual angulation of molars, overeruption of maxillary first molars, bone defects, and the capability of molar mesialization.

RESULTS

The vertical alveolar bone height in the missing group was reduced by 1.42 ± 0.70 mm, 1.31 ± 0.68, and 1.46 ± 0.85 mm on the buccal, middle, and lingual side, respectively (no differences among the three sides; p > 0.05). Alveolar bone width was reduced the greatest at the buccal CEJ level and the least at the lingual apex level. Mandibular second molar mesial tipping (with mean of the mesiodistal angulation = 57.47 ± 10.34°) and lingual tipping (with mean of the buccolingual angulation = 71.75 ± 8.34°) were observed. The mesial and distal cusps of maxillary first molars were extruded by 1.37 mm and 0.85 mm, respectively. Buccal and lingual defects of alveolar bone occurred at the CEJ, mid-root, and apex levels. Through 3D simulation, the second molar cannot be successfully mesialized into the missing tooth position, and the difference between the available and required distances for mesialization was the greatest at the CEJ level. The duration of tooth loss was significantly correlated with the mesio-distal angulation (R = -0.726, p < 0.001), buccal-lingual angulation (R = -0.528, p < 0.001) and the extrusion of the maxillary first molar (R = -0.334, p < 0.05).

CONCLUSION

Both vertical and horizontal resorption of alveolar bone occurred. Mandibular second molars exhibit mesial and lingual tipping. Lingual root torque and uprighting of the second molars are needed for the success of molar protraction. Bone augmentation is indicated for severely resorbed alveolar bone.

Survival Rate of 3-unit Fixed Partial Dentures Replacing First Molars: A Retrospective Cohort Study

Fixed partial dentures (FPDs) made of 12% Au-Pd alloy are covered under Japan's national health insurance system. The survival rate of such 3-unit fixed FPDs remains unknown, however. The purpose of this retrospective study was to assess their survival rate in the replacement of first molars. A total of 140 FPDs were included, and the endpoint was removal of an FPD. During the observation period, 43 FPDs were removed. The FPD survival rate was 70.2% at 10 yr, 58.2% at 15 yr, and 42.1% at 20 yr according to the Kaplan-Meier method. The estimated mean survival period was 19.4 yr. The main reasons for FPD loss were dental caries (27.9%), separation from the abutment tooth (18.6%), and pulpitis (18.6%). Single factor analysis using the log-rank test showed that two factors influenced FPD survival: a smaller gonial angle and deep pockets around the abutment teeth. This effect was not statistically significant in either case, however (p>0.05). The present results suggest that the prevention of caries and of the separation of the dentures from the abutment teeth are important factors in the long-term survival of FPDs.

Masticatory function in elderly compared to young adults

PURPOSE

To characterize the masticatory function of the elderly and to compare total amount of time, masticatory strokes and total mastication score among the elderly and young adults.

METHODS

It is an observational, cross-sectional and analytical study. A total of 50 individuals participated, 25 elderly (mean age 66 years) and 25 young adults (mean age 22 years). The evaluation of mastication was performed by standardized filming of the usual mastication of a wheat flour biscuit. The masticatory type (alternated bilateral, simultaneous bilateral, preferential unilateral, chronic and anterior), masticatory score, total masticatory time and the total number of masticatory strokes were verified and compared between the elderly and young adults.

RESULTS

The predominant masticatory pattern in the young adults was the alternated bilateral mastication (52%), while, in the elderly, the simultaneous bilateral mastication predominated (48%). The use of dental prostheses had a significant influence on the total mastication score; elderly presented greater masticatory time and greater amount of masticatory strokes; however, the total masticatory score was lower for this group.

CONCLUSION

The use of dental prosthesis has a significant influence on masticatory function. When compared to young adults, the elderly had a greater amount of time and masticatory strokes and a lower total mastication score.

Performance of crowns cemented on a fiber-reinforced composite framework 5-unit implant-supported prostheses: in silico and fatigue analyses

OBJECTIVE

To characterize the biomechanical performance of fiber-reinforced composite 5-unit implant-supported fixed dental prostheses (FDPs) receiving individually milled crowns by insilico and fatigue analyses.

METHODS

Eighteen implant-supported five-unit fiber-reinforced composite frameworks with an individually prepared abutment design were fabricated, and ninety resin-matrix ceramic crowns were milled to fit each abutment. FDPs were subjected to step-stress accelerated-life testing with load delivered at the center of the pontic and at 2nd molar and 1st premolar until failure. The reliability of the prostheses combining all loaded data and of each loaded tooth was estimated for a mission of 50,000 cycles at 300, 600 and 900 N. Weibull parameters were calculated and plotted. Fractographic and finite element analysis were performed.

RESULTS

Fatigue analysis demonstrated high probability of survival at 300 N, with no significant differences when the set load was increased to 600 and 900 N. 1st and 2nd molar dataset showed high reliability at 300 N, which remained high for the higher load missions; whereas 1st premolar dataset showed a significant decrease when the reliability at 300 N was compared to higher load missions. The characteristic-strength of the combined dataset was 1252 N, with 1st molar dataset presenting higher values relative to 2nd molar and 1st premolar, both significantly different. Failure modes comprised chiefly cohesive fracture within the crown material originated from cracks at the occlusal area, matching the maximum principal strain location.

SIGNIFICANCE

Five-unit implant-supported FDP with crowns individually cemented in a fiber-reinforced composite framework presented a high survival probability. Crown fracture comprised the main failure mode.

The impact of occluding pairs on the chewing patterns among the elderly

OBJECTIVES

This study aims to investigate the impact of occluding pairs (OPs) on chewing strokes, chewing time, mealtime duration, and bite force in an aging population.

METHODS

The 100 participants included 52 women and 48 men with average age of 71.2 years. The subjects were restricted to those who can eat what they wanted and had no temporomandibular joint disorder (TMD) and dysphagia history; their OPs were counted in the posterior occlusal support zone in accordance with the Eichner classification. Free habitual mastication of a cornstarch cookie was analyzed by recording the number of chewing strokes and the amount of time needed for complete mastication. Strokes were counted by considering the opening and closing mandibular movements. Mealtime was defined as the time spent to finish a lunchbox and accomplish swallowing. Bite force was estimated with a T-Scan III®. A linear regression analysis was used to evaluate the impact of the OPs on the chewing strokes, chewing time, mealtime duration, and bite force.

RESULTS

In this study, 76% of the participants had 4 OPs and 12% participants had 3 OPs. Increasing the OPs significantly shortened the chewing time and mealtime duration (P = 0.02). The mealtime duration did not notably affect the chewing time (P = 0.237). There was significant association between OPs and bite force (P < 0.0001).

CONCLUSIONS

In elderly, increasing OPs significantly raised the bite force and shortened the chewing time and strokes. More OPs might be the key to maintain good chewing function.

CLINICAL SIGNIFICANCE

Among the elderly, increasing OPs significantly raised the bite force and shortened the chewing time and mealtime duration. To provide better chewing function, good oral hygiene is important to maintain as many OPs as possible; how to gain more OPs is essential concern in the prosthodontic treatment plan making.

Impact of the Serum Level of Albumin and Self-Assessed Chewing Ability on Mortality, QOL, and ADLs for Community-Dwelling Older Adults at the Age of 85: A 15 Year Follow up Study

Quality of life (QOL) and mortality are true endpoints of epidemiological or medical research, especially for community-dwelling older adults. Nutritional status and activities of daily living (ADLs) are associated with QOL and mortality. Good oral health status supports a good nutritional status. The aim of this study was to elucidate the complex structure of these important health-related factors. We surveyed 354 healthy older adults at the age of 85. Nutritional status was evaluated by the serum level of albumin. QOL, ADLs, self-assessed chewing ability, serum albumin level, and mortality during the 15 year follow up period were analyzed. Self-assessed chewing ability was associated with QOL and ADLs. Self-assessed chewing ability for slight-hard foods was associated with mortality in men. However, it was not associated with the serum albumin level. The serum albumin level was associated with mortality in women. These results indicate that maintaining good oral function is not enough. Nutritional instruction in accordance with oral function is indispensable for health promotion in older adults. When planning health promotion strategies for older adults, different strategies are needed for men and women.

Failure Modes and Survival of Anterior Crowns Supported by Narrow Implant Systems

The reduced hardware design of narrow implants increases the risk of fracture not only of the implant itself but also of the prosthetic constituents. Hence, the current study is aimed at estimating the probability of survival of anterior crowns supported by different narrow implant systems. Three different narrow implant systems of internal conical connections were evaluated (Ø3.5 × 10 mm): (i) Active (Nobel Biocare), (ii) Epikut (S.I.N. Implant System), and (iii) BLX (Straumann). Abutments were torqued to the implants, and standardized maxillary incisor crowns were cemented. The assemblies were subjected to step-stress accelerated life testing (SSALT) in water through load application of 30 degrees off-axis lingually at the incisal edge of the crowns using a flat tungsten carbide indenter until fracture or suspension. The use level probability Weibull curves and reliability for completion of a mission of 100,000 cycles at 80 N and 120 N were calculated and plotted. Weibull modulus and characteristic strength were also calculated and plotted. Fractured samples were analyzed in a stereomicroscope. The beta (β) values were 1.6 (0.9-3.1) and 1.4 (0.9-2.2) for BLX and Active implants, respectively, and 0.5 (0.3-0.8) for the Epikut implant, indicating that failures were mainly associated with fatigue damage accumulation in the formers, but more likely associated with material strength in the latter. All narrow implant systems showed high probability of survival (≥95%, CI: 85-100%) at 80 and 120 N, without significant difference between them. Weibull modulus ranged from 6 to 14. The characteristic strength of Active, Epikut, and BLX was 271 (260-282) N, 216 (205-228) N, and 275 (264-285) N, respectively. The failure mode predominantly involved abutment and/or abutment screw fracture, whereas no narrow implant was fractured. Therefore, all narrow implant systems exhibited a high probability of survival for anterior physiologic masticatory forces, and failures were restricted to abutment and abutment screw.

Effects of self-assessed chewing ability, tooth loss and serum albumin on mortality in 80-year-old individuals: a 20-year follow-up study

Background

The association between dental status and mortality in community-dwelling older adults has been documented by several studies. The aim of this study was to analyze the contribution of self-assessed chewing ability, number of remaining teeth and serum albumin levels to mortality and the interactions between the three factors.

Methods

A 20-year follow-up study was conducted with 666 subjects aged 80 years (from 1996 to 2017) who resided in the 8 areas served by one health center in Iwate Prefecture. Health check-ups including physical fitness measurements were conducted at a meeting place or gymnasium. Medical interview and blood sampling were conducted by physician. Oral examination was examined by dentist. The number of remaining teeth, serum albumin levels, and self-assessed chewing ability were used as predictors of mortality.

Results

Among the 608 subjects (233 men and 375 women) included in this study, only 12 subjects (1.97%) survived after 20 years of follow-up. For men, dental status and serum levels of albumin were significantly associated with mortality. The hazard ratios of self-assessed chewing ability calculated by item response theory analysis and the inability to chew at least one food adjusted for serum albumin and tooth conditions were statistically significant in men. When adjusted by health status evaluated by blood tests, self-assessed chewing ability was statistically significant in men. According to path analysis, self-assessed chewing ability and serum albumin independently affected mortality in men.

Conclusion

Masticatory dysfunction may be an important risk factor for mortality in men, even though it was self-assessed. Retaining chewing ability might be a useful predictor of longevity in older male adults.

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.

Dental status, oral prosthesis and chewing ability in an adult and elderly population in southern Brazil

OBJECTIVE

The objective of this study was to explore the factors associated with inadequate chewing in an adult and elderly population of a city in the southern region of Brazil.

METHODS

This was a cross-sectional study based on a population home-based inquiry (DCH-POP) in southern Brazil. Individuals were interviewed by trained interviewers to create a standardized procedure. In a pilot study, the Questionnaire of Human Communication Disorders (DCH-POP) was created and validated to identify self-reported speech and language, swallowing and hearing disorders. The outcome was dichotomized into either having adequate chewing or not, as assessed by a series of questions about chewing ability. Analyses of absolute and relative frequencies were measured according to the studied variables. A Poisson regression was applied at a significance level of 5%.

RESULTS

A total of 1,246 people were interviewed. Inadequate chewing was found in 52 (5.6%) individuals, with a higher prevalence in the elderly (11.8%) than in adults (5.2%). In the final model, the following factors were associated with inadequate chewing: being 61 years of age or older (prevalence ratio or PR=9.03; 95% CI: 1.20-67.91), loss of teeth and use of unadjusted prosthesis (PR=3.50; 95% CI: 1.54-7.95), preference for foods of soft consistency (PR=9.34; 95% CI:4.66-8.70) and difficulty in nasal breathing (PR=2.82; 95% CI: 1.31-6.06).

CONCLUSION

Age, oral health status through dental prosthesis, preference for foods of soft consistency and difficulty breathing through the nose were factors associated with chewing inability in adults and the elderly.