The Ruminant sorting mechanism protects teeth from abrasives.

Dental wear due to ingestion of dust and grit has deleterious consequences. Herbivores that could not wash their food hence had to evolve particularly durable teeth, in parallel to the evolution of dental chewing surface complexity to increase chewing efficacy. The rumen sorting mechanism increases chewing efficacy beyond that reached by any other mammal and has been hypothesized to also offer an internal washing mechanism, which would be an outstanding example of an additional advantage by a physiological adaptation, but in vivo evidence is lacking so far. Here, we investigated four cannulated, live cows that received a diet to which sand was added. Silica in swallowed food and feces reflected experimental dietary sand contamination, whereas the regurgitate submitted to rumination remained close to the silica levels of the basal food. This helps explain how ruminants are able to tolerate high levels of dust or grit in their diet, with less high-crowned teeth than nonruminants in the same habitat. Palaeo-reconstructions based on dental morphology and dental wear traces need to take the ruminants' wear-protection mechanism into account. The inadvertent advantage likely contributed to the ruminants' current success in terms of species diversity.

Evaluation of masticatory performance and patient satisfaction for conventional and 3D-printed implant overdentures: a randomized crossover study.

BACKGROUND: This crossover clinical study aimed to evaluate and compare masticatory performance and patient satisfaction for patients rehabilitated with conventional heat-cured acrylic resin and 3D-printed mandibular implant overdentures retained with bar attachment. MATERIALS AND METHODS: Sixteen completely edentulous healthy participants received new conventional dentures. In the mandible, four interforaminal implants were inserted. Following the stage of osseointegration, the bar was constructed in a trapezoidal configuration. Each patient randomly received the following overdentures using a crossover design: (1) conventional heat-cured acrylic resin overdenture and (2) 3D-printed overdenture (developed by scanning of mandibular conventional overdenture). The masticatory performance was assessed by conducting a two-colour mixing ability test at 5, 10, 20, 30, and 50 masticatory cycles. Moreover, the McGill Denture Satisfaction Questionnaire (MDSQ) was employed to assess patient satisfaction. Evaluation was performed after 3 months of using each overdenture. Paired sample t tests were used to compare the masticatory performance and MDSQ scores of patients for both prostheses. RESULTS: No significant difference in masticatory performance was reported between the two types of overdentures. Regarding patient satisfaction, only the esthetic aspect was significantly better for conventionally processed overdentures than for printed overdentures. Insignificant differences were observed regarding other MDSQ items between the two overdentures. CONCLUSION: Within this clinical study, 3D-printed implant overdentures showed promising results in terms of chewing efficiency and patient satisfaction compared to conventionally fabricated implant overdentures. TRIAL REGISTRATION: Retrospectively registered at www. CLINICALTRIALS: gov : NCT06148727.(28/11/2023).

Subjective and Objective Assessment of Chewing Performance in Older Adults with Different Dental Occlusion.

OBJECTIVES: Satisfactory masticatory function is a significant indicator of improved oral health-related quality of life in older adults, either with or without artificial teeth. The purpose of this study was to examine masticatory performance of older adults with different prosthodontic reconstructions and occlusion, as well as to compare subjective and objective assessment of chewing performance. MATERIAL AND METHODS: This study included 100 participants aged 65 and more. The chewing function questionnaire (CFQ) with answers on the Likert scale 0-4 (0 = no difficulties; 4 = maximum difficulties) was used as an indicator of subjective masticatory assessment. The two-color chewing gum test was used as objective assessment of masticatory function (mixing ability), based on the Z-score values. Dental occlusion was assessed using functional teeth units (FTU). RESULTS: The results obtained using the CFQ and the clinical mixing ability test are in compliance with each other (r = 0.742). A decrease in the number of natural teeth, especially posterior teeth, progressively reduced chewing ability and increased difficulties in mastication. Participants with less FTUs, or with FTUs that are a part of removable denture, had greater reduction in masticatory function compared to those with FTUs composed of natural teeth or fixed partial dentures. CONCLUSION: This study revealed a strong positive correlation between the subjective masticatory assessment in older adults using the validated questionnaire and the objective clinical test of the mixing ability of two chewing gums. Our data on influence of the number and the type of FTU on masticatory performance will be valuable when planning prosthodontic therapy.

Effectiveness evaluation of autotransplanted teeth after performing extraoral endodontic surgery instead of conventional root canal therapy.

PURPOSE: The aim of this study was to examine the viability and efficacy of utilizing extraoral apicoectomy and retrograde filling in combination to seal the root canal system of mature molars without the need for root canal therapy (RCT) during the autotransplantation of teeth (ATT). MATERIALS AND METHODS: This study screened 27 patients who received ATT at the Department of Oral Surgery in the Hospital of Stomatology from 2019 to 2021. Extraoral apicoectomy and retrograde filling were performed, while RCT was temporarily not performed. The study analysed the periodontal status and masticatory function of transplanted teeth one to three years postoperation and used cone-beam computed tomography (CBCT) and periapical radiograph (PA) to evaluate the integrity of the periodontal space and intra/periapical inflammation. The potential predictors of survival/success were analysed statistically. We also conducted questionnaires and chewing efficiency tests. RESULTS: In this study, 27 TTs from 27 patients were found to be fully functional in terms of chewing ability. The overall survival rate was 100% (27/27), and the success rate was 70.4% (19/27). A total of 90.9% (20/22) of patients reported being satisfied or very satisfied with their TTs. Additionally, the chewing efficiency of the transplantation side was on average 82.0% of that of the healthy side, with a significant difference between the two sides (P < 0.05). None of the potential predictors were found to significantly affect the success or survival of the transplanted tooth (TT). CONCLUSION: The combination of extraoral apicoectomy and retrograde filling in TT showed promising outcomes, but further clinical cases and longer follow-up times are still required to validate the treatment plan.

Chewing and its influence on swallowing, gastrointestinal and nutrition-related factors: a systematic review.

The study aimed to evaluate the hypothesis that chewing is a mechanical and physiological contributor to swallowing, physiologic/pathologic processes of the gastrointestinal tract (GIT), and nutrition-related factors. A search strategy was applied to three different databases to investigate if chewing function in adults affects the swallowing, physiologic/pathologic processes of the GIT, and nutrition-related factors compared to controls with no exposure. The included studies were evaluated for methodological quality and risk of bias and certainty of evidence. The results showed 71 eligible studies. Overall, the results showed that 46 studies supported the hypothesis while 25 refuted it. However, the GRADE analysis showed low to very low certainty of the evidence to support the hypothesis that chewing is an important contributor in the swallowing process, and physiologic/pathologic processes in the GIT. The GRADE analysis also showed a moderate to very low certainty of the evidence to suggest that chewing function contributes to nutrition-related parameters. The overall results of the current study showed that a majority (64.7%) of the studies (46 out of 71) supported the hypothesis. However, robust studies with proper design, adequate sample size, and well-defined outcome parameters are needed to establish conclusive evidence.

Use of handgrip strength measurement as an alternative for assessing chewing function in people with dementia.

BACKGROUND: Chewing ability and handgrip strength can be independent explanatory factors of physical fitness. The usability of measurement procedures for assessing chewing function in people with dementia seems to be limited. This study aimed to show an association between handgrip strength and chewing function to enable the use of handgrip strength measurement as an alternative for determining chewing parameters in people with dementia.  METHODS: The data analysed here are part of the OrBiD (Oral Health, Bite Force and Dementia) pilot study. A total of 120 participants were assigned to five evaluation groups based on their cognitive abilities using the Mini-Mental State Examination (MMSE). The MMSE groups in this data analysis were "no dementia" (noDem, MMSE 28-30), "mild cognitive impairment" (mCI, MMSE 25-27), and "mild dementia" (mDem, MMSE 18-24). Handgrip strength, maximum occlusal force, and chewing efficiency were measured.  RESULTS: The Mini-Mental State Examination scores among all participants (n = 71) resulted in a median of 27 and a range of 18-30. An association between maximum handgrip strength and the cognitive impairment of the participants was shown. Nevertheless, the use of handgrip strength measurement as an alternative for determining chewing function was not verified in this study. CONCLUSIONS: The feasibility and reliability of chewing function measurements in people with dementia should be investigated. Existing measurement procedures may need to be adapted or new assessments may need to be developed to be usable in people with dementia. TRIAL REGISTRATION: ClinicalTrials.gov NCT03775772.

Variation in chewing efficiency of Yakushima Japanese macaque (Macaca fuscata yakui).

OBJECTIVES: Chewing efficiency plays an important role in the survival and distribution of primates. Yet, little is known about the intra-specific variation of chewing efficiency. The purpose of this study is to report the pattern of seasonal and regional variation in chewing efficiency among Yakushima Japanese macaques (Macaca fuscata yakui). MATERIALS AND METHODS: Fecal samples of Yakushima Japanese macaques were collected from lowland, highland and summit areas in Yakushima between July 2015 and March 2016 (n = 236). Using sieving analysis, we compared fecal particle size (dMEAN) and proportion of finest particles p(0) between different geographical areas and seasons. RESULTS: Seasonally, in the lowland zone, there was a non-significant decrease in dMEAN during spring, while p(0) was significantly higher during summer than it was during winter and spring. Regionally, dMEAN was higher in the summit zone than it was in other areas during autumn, while p(0) was also higher in the summit zone. CONCLUSIONS: While seasonal variation in dMEAN can be explained by the reported difference in the proportions of food categories in diet between seasons, its influence is mitigated, possibly by the selective feeding of less mechanically challenging parts in each category. Regional variation in dMEAN and p(0) may be the results of bamboo consumption in this area. Combining our data with studies that focus on seasonal and regional variations of food properties or gut microbes might provide a better understanding of the relation between diet, chewing and digestion in Yakushima macaques.

Changes in conditions related to reported oral and general health over a ten-year period as reflected in two cohorts of 75-year-old subjects examined in 2007 and 2017.

BACKGROUND: The rapidly ageing and increasingly dentate population puts great demands on society regarding the provision of adequate medical and dental care facilities. OBJECTIVES: To present changes in reported demographic, general and oral health factors in two cohorts of 75 year olds in 2007 and 2017, and to analyse factors associated with self-reported number of remaining teeth and chewing efficiency. MATERIAL AND METHODS: All 75-year-old people living in two Swedish counties received a questionnaire in 2007 and in 2017. The response rates in 2007 and in 2017 were 71.9% (n = 3735) and 70.7% (n = 5091), respectively. Reported number of teeth was clinically validated in a selected subgroup. RESULTS: The 2017 cohort reported significantly better general health and dental state. Edentulousness was 7.8% in 2007 and 2.3% in 2017, while 'very good' chewing efficiency was 55.2% and 60.5%, respectively. Born outside Sweden, single living, not feeling healthy and smoking predicted reduced number of teeth in both cohorts. Impaired chewing efficiency in both cohorts was predicted by being born outside Sweden, lower education, not feeling healthy, reduced number of teeth and denture wearing. CONCLUSIONS: Seventy-five-year-old people in Sweden reported much better oral and general health in 2017 compared to 2007. In 2017, 75% had practically all natural teeth present and only 2% were edentulous. This development of an increasingly dentate and partially dentate ageing population will put high demands on the oral healthcare system and will need adapting undergraduate/postgraduate education and management strategies to meet the requirements of the elderly.

The effects of prosthetic status and dementia on the chewing efficiency of seniors in nursing homes.

BACKGROUND: The oral health of seniors in nursing homes is compromised. Furthermore, reduced chewing efficiency is described to be associated with reduced cognition. However, studies investigating how prosthetic status affects the chewing efficiency of nursing home residents are not available. OBJECTIVE: To evaluate associations between prosthetic status, dementia and chewing efficiency of seniors in nursing homes. METHODS: This study was performed in nine nursing homes. In addition to assessing the general and medical data of the participants, a dental examination was assessed and the severity of dementia was evaluated by use of the Clinical Dementia Rating (CDR). Furthermore, chewing efficiency was assessed by use of a two-colour mixing ability test. Descriptive and bivariate statistics, as well as linear regression models with the dependent variable chewing efficiency and possible confounders, were used to analyse data at P < .05. RESULTS: Complete target variables of 146 participants were analysed. The mean (SD) chewing efficiency of the study sample, as expressed by the variance of hue, was .590 (.250). The type of prosthesis used (P < .001), the number of occluding tooth pairs (P < .001) and the presence of dementia (P = .002) were the main variables significantly affecting chewing efficiency. The condition of removable dentures also had an effect (P = .016). Multivariate testing predominantly confirmed these associations. CONCLUSION: The chewing efficiency of seniors in nursing homes is somewhat compromised. Beyond dental aspects, suffering from dementia seems to reduce the chewing efficiency. Further interventional/longitudinal studies are, however, encouraged to verify this outcome.

Comparative evaluation of biting force and chewing efficiency of all-on-four treatment concept with other treatment modalities in completely edentulous individuals.

AIM: To compare and evaluate biting force and chewing efficiency of all-on-four treatment concept, implant-supported overdenture, and conventional complete denture. SETTINGS AND DESIGN: Invivo - comparative study. MATERIALS AND METHODS: A total of 12 edentulous patients were included in the study and conventional complete dentures were fabricated. Patients were divided into two groups. In Group 1, complete dentures were replaced with implant-supported overdenture, and in Group 2, complete dentures were replaced with hybrid denture supported by all-on-four treatment concept. The biting force was assessed using a bite force sensor and electromyographic recordings were made by electromyogram for masticatory muscles when chewing three different consistencies of foods. STATISTICAL ANALYSIS USED: The data was statistically analyzed using software SPSS version 22.0. Paired t-test was used for intra-group comparison and unpaired t-test was used for intergroup comparison. RESULTS: The difference in biting force and chewing efficiency for all-on-four treatment concept was statistically significant for overdenture and complete denture. The highest biting force and chewing efficiency were observed for all-on-four treatment concept, followed by implant-supported overdenture and complete denture. CONCLUSION: The study concluded that the completely edentulous individuals with atrophic posterior alveolar ridges can be rehabilitated successfully with improved biting force and chewing efficiency by All-on-four treatment concept.

[Development and validation of the Mini Dental Assessment : A procedure for improved estimation of need for dental treatment in geriatrics]. / Entwicklung und Validierung des "Mini Dental Assessment" : Ein Verfahren zur besseren Einschätzung des zahnärztlichen Behandlungsbedarfes in der Geriatrie.

BACKGROUND: In the future there will be an increasing demand for professional care with simultaneous retention of the dentition in older people. Due to inadequate dental knowledge, it is often not possible for caregivers to adequately assess dental deficits. OBJECTIVE: The aim of the study was to develop and validate a simple tool (Mini Dental Assessment, MDA) to assess possible dental treatment needs (DTN) of residential geriatric facilities by nursing personnel. MATERIAL AND METHODS: In the study 169 patients (51 from the University Hospital Giessen, 118 from the Bonifatius Hospital Lingen) underwent a dental examination. The dental status was evaluated based on the California Dental Association (CDA) criteria and the DTN determined. In addition, the time since the patients last visit to a dentist (TLVD) and denture age (DA) were documented and a chewing function test (carrot eating test, CET) was carried out. In a second study 155 patients were examined (115 from the University Hospital Giessen, 40 from the Bonifatius Hospital Lingen) corresponding to the reference sample and including a further chewing function test (after Schimmel und Slavicek) and questionnaires on quality of life (Oral Health Impact Profile (OHIP), Denatl Impact on Daily Living (DiDDL)). RESULTS: A total of 108 patients required dental treatment. The mean value (±SD) for the TLVD was 2.5 ± 3.8 years and 10.8 ± 8.9 years for the DA. There was a positive correlation (Spearman, P < 0.005) between the DTN and degree of comminution in the CET (3.4 ± 1.8 grade). Based on the results an assessment tool was developed using the variables CET, TLVD and DA weighted by the respective regression coefficients (10:3:1). The resulting mean total MDA score was 51.32 ± 28.14. A sensitivity/specificity analysis was conducted and a receiver operating characteristic (ROC) curve calculated (area under curve, AUC: 0.805; 95% CI: 0.738-0.873). The ROC curve from the follow-up study showed a good agreement with the ROC curve from the reference study (AUC 0.829, 95% CI: 0.751-0.907). CONCLUSION: Based on the results of the study it could be shown that the MDA is a suitable instrument for making a valid statement on the assessment of DTN of patients in long-term care facilities. The validation study revealed the validity of the MDA in its originally developed form and the addition of two further chewing function tests did not significantly improve the validity of the MDA. Overall, the MDA appears to be an appropriate tool to help nursing home personnel to assess the necessity for nursing home residents to visit a dentist.

Masticatory efficiency of implant-supported removable partial dental prostheses in patients with free fibula flap reconstructed mandibles: A split-mouth, observational study.

OBJECTIVES: The aim of this split-mouth study was to evaluate the masticatory efficiency in patients with segmentally reconstructed mandibles using free fibula flaps, with and without stabilizing osteosynthesis material in-situ during implant placement for rehabilitation with implant-supported removable partial dental prostheses (ISRPDPs). METHODS: Ten participants (n = 10; ♀ = 2, ♂ = 8; mean age = 38.1 years) consented to participate in this study. The participants' normal side (Side N) of the mandible served as the control side, for comparing the masticatory efficiency of the segmentally reconstructed and rehabilitated side (Side R). Masticatory efficiency was evaluated using the two-colored chewing gum test, measured as subjective assessment (SA) and electronically evaluated variance of hue (VOH). Data were checked for normal distribution and statistically analyzed with the level of significance set to p < 0.05. RESULTS: Thirty-four tissue-level implants were placed in reconstructed mandibles of 10 participants. There was no significant difference observed in the masticatory efficiencies between Side N and Side R, in both subjective and electronic assessments. No implant loss was observed after a post-rehabilitated mean follow-up period of 42.7 months, revealing an implant survival rate of 100%. CONCLUSIONS: In patients with surgically reconstructed mandibles, a normal masticatory function can be successfully achieved with a rehabilitation of the reconstructed side with implant-supported removable partial dental prostheses. Implant-supported prostheses should be actively advocated in patients with reconstructive surgeries to restore their masticatory function, extend their food choices, and improve their overall oral health-related quality of life.

Validation of a purpose-built chewing gum and smartphone application to evaluate chewing efficiency.

OBJECTIVES: To validate a purpose-built two-coloured chewing gum (Hue-Check Gum® ), and to test the accuracy of a custom-built smartphone application for a colour-mixing ability test to assess chewing function. METHODS: Fully dentate participants (28D-group) and edentulous participants with implant overdentures (IOD-group) were recruited. They chewed a Hue-Check Gum® for 5, 10, 20, 30 and 50 chewing cycles, respectively. Maximum voluntary bite force (MBF) was assessed with a digital gauge. The specimens were analysed according to their colour mixture (variance of hue, VOH) with a validated software (VOH_scan) and a newly developed smartphone application (VOH_app). RESULTS: Participants segregated by dental state were significantly different regarding the number of occluding pairs of teeth, age and MBF. VOH_scan showed a negative logarithmic association with the number of chewing cycles, and VOH could be predicted from chewing cycles, MBF and gender. The clearest discrimination between the IOD and the 28D groups was observed for n = 20 chewing cycles; at this point, VOH was distinguishably different with a P-value < 0.0001. The VOH_app was a very good predictor for VOH_scan with 0.80 < pseudo-R2  < 0.83, depending on light exposure and measuring distance. There was, however, a systematic error in the accuracy of the app for inadequately chewed specimens. CONCLUSIONS: The use of the two-coloured chewing gum would provide a fast, simple and inexpensive method for the assessment of masticatory performance, which could be used in geriatric wards or in private practices without the requirement of specialised equipment or trained staff.

Short-term changes in chewing efficiency and subjective evaluation in normal dentate subjects after insertion of oral appliances with an occlusal flat table.

Oral appliances with an occlusal flat table are used as treatment dentures. However, the short-term effect of insertion of such oral appliances on chewing has not been reported. This study aimed to determine whether experimental and continuous insertion of oral appliances with an occlusal flat table has an effect on chewing efficiency and Oral Health Impact Profile (OHIP) in healthy participants. Ten participants each in the oral-appliance and control (no oral-appliance insertion) groups attended six data collection sessions for 5 consecutive days. Participants answered the OHIP questionnaire and underwent the chewing efficiency test. For each parameter, intergroup differences were investigated in terms of change from baseline to immediately after oral-appliance insertion (0 hour; P < .05) and from 0 hour to 24, 48, 72 and 96 hours after oral-appliance insertion (P < .05). There were significant differences between groups in the degree of change in chewing efficiency and OHIP scores for functional limitation, physical pain, physical disability and handicap from baseline to 0 hour (all, P < .001); among these, only OHIP scores for functional limitation and physical pain demonstrated significant differences in degree of change between the two groups at 96 hours after appliance insertion (P = .477 and .275, respectively). Differences between the two groups in the degree of change in other parameters were not significant. Insertion of oral appliances caused a decrease in chewing efficiency and an increase in OHIP scores. Continuous insertion improved functional limitation and physical pain within 96 hours.

Faecal Particle Size in Free-Ranging Proboscis Monkeys, Nasalis larvatus: Variation between Seasons.

Reducing the size of food particles is crucial for herbivores. Seasonal dietary changes are known to influence animals' chewing efficiency. Proboscis monkeys (Nasalis larvatus) are foregut fermenters, with a high chewing efficiency allowing them to achieve very fine faecal particles. In this study, we investigated how proboscis monkeys' chewing efficiency varies between wet and dry seasons, hypothesising differences possibly related to diet change. Faecal particle size analysis is an established approach to estimate chewing efficiency in mammalian herbivores. We analysed 113 proboscis monkey faecal samples collected in the Lower Kinabatangan Wildlife Sanctuary, between 2015 and 2017. By following standard sieve analysis protocols, we measured a mean particle size MPS0.025-8 of 0.45 ± 0.14 mm, and confirmed a previous result that proboscis monkeys have a very low faecal MPS. This study highlights a seasonal influence on proboscis monkeys' chewing efficiency, with smaller MPS (better chewing efficiency) during the wet season. During that time of the year, individuals may potentially change their diet, as all faecal samples contained intact seeds. Whether the seasonal MPS difference in proboscis monkeys is smaller than in other colobines due to their "rumination" strategy remains to be investigated.

Chewing efficiency and maximum bite force with different attachment systems of implant overdentures: a crossover study.

PURPOSE: This crossover study aimed to evaluate and compare chewing efficiency and maximum bite force (MBF) with resilient telescopic and bar attachment systems of implant overdentures in patients with atrophied mandibles. MATERIAL AND METHODS: Ten participants with severely resorbed mandibles and persistent denture problems received new maxillary and mandibular conventional dentures (control, CD). After 3 months of adaptation, two implants were inserted in canine region of the mandible. In a quasi-random method, overdentures were connected to the implants with either bar overdentures (BOD) or resilient telescopic overdentures (TOD) attachment systems. Chewing efficiency in terms of unmixed fraction (UF) was measured using chewing gum (after 5, 10, 20, 30 and 50 strokes), and MBF was measured using a bite force transducer. Measurements were performed 3 months after using each of the following prostheses: CD, BOD and TOD. RESULTS: Chewing efficiency and MBF increased significantly with BOD and TOD compared to CD. As the number of chewing cycles increased, the UF decreased. TOD recorded significant higher chewing efficiency and MBF than BOD. CONCLUSION: Resilient telescopic attachments are associated with increased chewing efficiency and MBF compared bar attachments when used to retain overdentures to the implants in patients with atrophied mandibles.

A comparative evaluation of chewing efficiency, masticatory bite force, and patient satisfaction between conventional denture and implant-supported mandibular overdenture: An in vivo study.

PURPOSE: The purpose of this within-subject crossover clinical trial was to compare and evaluate the chewing efficiency, masticatory bite force, and patient satisfaction with conventional dentures and two implant-retained mandible overdentures after 4 weeks of usage. METHOD: This within-subject crossover clinical trial was carried out in the Department of Prosthodontics in K.D Dental College and Hospital. A total 15 patients were selected for the study. To report the changes in chewing efficiency by chewing 6gms of peanuts with 40 chewing strokes and comparing the particle size of the chewed material between two implant retained mandibular overdenture with that of conventional denture using micro vu excel gantry type visual measurement machine. To report changes in masticatory bite force after transition of conventional complete denture patient to implant retained overdenture after using the prosthesis for four weeks each and recorded by digital transducer. To assess the patient satisfaction after transition of conventional complete denture patient to implant retained mandibular overdenture with help of OHIP edent patient satisfaction questionnaire. RESULTS: The chewing efficiency for implant retained overdenture increased significantly than that of conventional denture. The particle size decreased to 76.34% for implant supported overdenture than that of conventional denture. The chewing strokes required by conventional denture was 69 strokes and that by implant supported overdenture which was 40 strokes to get the same mean particle size. The patients satisfaction after receiving the implant retained overdenture was significantly higher than that of complete denture. CONCLUSION: The provision of two mandibular implants significantly improves measures of oral function and better quality of life for edentulous patients.

Implant placement under existing removable dental prostheses and its effect on masticatory performance.

OBJECTIVE: The aim of this within-subject study was to evaluate the outcome with implant-tooth-supported removable partial dental prostheses (RPDP group) and implant-supported removable complete dental prostheses (edentulous group) in terms of masticatory performance and self-assessment. MATERIALS AND METHODS: Thirty patients participated in this prospective clinical study (RPDP group: n = 12; edentulous group: n = 18). The prostheses were supported in strategically advantageous regions by placing implants with ball attachments and corresponding matrices in the existing dentures. The masticatory performance was evaluated with the Swallowing Threshold Test Index (STTI), the number of chewing strokes, and the time needed until swallowing at pre-treatment and 6 weeks after integration of ball attachments. Additionally, patients scored chewing satisfaction before and after implantation on a visual analogue scale. RESULTS: The STTI increased significantly (p ≤ 0.05) after implant therapy in the edentulous group but not in the RPDP group. Furthermore, the STTI was significantly higher (p ≤ 0.05) in the RPDP group than in the edentulous group at pre-treatment, however, not after therapy (P > 0.05). All patients were very satisfied after therapy concerning ability of speaking, chewing, and stability of their prosthesis. CONCLUSIONS: Patients of the edentulous group benefit more from strategically placed implants under the existing dentures than patients from the RPDP group. However, according to the subjective assessment, the chewing satisfaction generally increased for both groups after implant therapy. CLINICAL RELEVANCE: Patients with a strongly reduced dentition and edentulous patients benefit from strategically placed implants under the existing removable dentures.

Chewing efficiency and electromyographic activity of masseter muscle with three designs of implant-supported mandibular overdentures. A cross-over study.

PURPOSE: The aim of this study was to compare the effect of three designs for implant-supported mandibular overdenture on the chewing efficiency and electromyographic (EMG) activity of masseter muscles. MATERIAL AND METHODS: Eighteen edentulous patients received new maxillary and mandibular dentures (control, CD) before implant placement. After using the dentures for 3 months, patients were randomly divided into six blocks (three patients/block) and received four implants in canine and first molar areas of the mandible. Following osseointegration period, new duplicate mandibular overdentures were successively connected to the implants with: (i) ball attachment on two implants (2BOD), (ii) bar attachment on two implants (2ROD), and (iii) bar attachments on four implants (4ROD) in a random order. Chewing efficiency was measured using chewing gum, and EMG was recorded during clenching (with or without food). Evaluations were made 3 months after using each of the following prostheses: CD, 2BOD, 2ROD, and 4ROD. RESULTS: All implant-supported overdentures showed a significant increase in chewing efficiency and EMG values when compared to CD. These values increased significantly with 4ROD when compared to 2BOD or 2ROD prostheses. There was no significant difference in chewing efficiency and EMG between 2BOD and 2ROD prostheses. CONCLUSION: Four-implant-supported overdentures seem to present a functional advantage vs. two-implant-supported overdentures, independent of the chosen attachment system.

Chewing efficiency and contact area discrepancies in Angle's class I and II malocclusion: A comparative study.

Objective: The study aimed to assess and compare both the chewing efficiency and the contact area between class I and class II of Angle's malocclusions. Material and methods: A total of 120 individuals aged between 19 and 30 years were examined and were divided into two groups according to Angle's class (Class I and class II). The chewing efficiency was quantified using the ViewGum software and two-colored chewing gum. The contact area was quantified using modeling wax and MATLAB software. All data were collected, then, analyzed using SPSS software 21. Data normality was checked through kurtosis test. Descriptive results were calculated. Matched sample t-tests were used to compare chewing efficiency measurements between right and left sides. Independent t-tests were used to compare chewing efficiency and the contact area between class I and class II of Angle's malocclusions. Linear regression and Pearson correlation were used to assess the correlation between chewing efficiency and the contact area. The significance level was fixed at p = 0.05. Results: For group 1, the mean hue value on both sides was 0.086 ± 0.058. For group 2, it was 0.095 ± 0.055. The difference between both groups was statistically significant (p = 0.03). For group 1, the mean contact area was 49.91 ± 21.47 mm2. For group 2, it was 51.42 ± 19.76 mm2. The difference was statistically not significant (p = 0.4). The correlation between the contact area and the chewing efficiency in both groups was statistically significant and it was negative (in class I p = 0 and R = -0.616; in class II p = 0.01 and R = -0.408). Conclusion: The Chewing is better for patients with Angle's Class I malocclusion. The contact area is higher. Larger occlusal contact area leads to higher masticatory efficiency. Further studies should be conducted.