EMG correlations of edentulous patients with implant overdentures and fixed dental prostheses compared to conventional complete dentures and dentates: a systematic review and meta-analysis

Tooth Loss in Periodontitis Patients-A Risk Factor for Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

Periodontal disease and tooth loss have been long suggested as risk factors of mild cognitive impairment. The underlying mechanisms could be systemic chronic inflammatory mediators, direct pathologic challenge to the nervous system, malnutrition and/or loss of neurosensory stimulation input causing brain atrophy. This review aimed to examine the existing literature studies linking the effect of periodontal disease and tooth loss on the development of mild cognitive impairment.

METHODS

A systematic review using PEO was conducted. Three electronic databases, namely Embase, Medline and DOSS (UCLan), were searched for relevant articles published up to April 2023. Google Scholar and a hand search were also conducted to ensure no relevant studies had been missed. The Newcastle-Ottawa scale was used to assess the quality of studies.

RESULTS

The findings showed that chronic periodontitis and tooth loss, both individually and in combination, led to an increased risk of mild cognitive decline in adults over 50 years. Within the limitations of this review, periodontitis and tooth loss both contribute to an increased risk of mild cognitive impairment and dementia, but the evidence so far is not strong.

CONCLUSIONS

In future, more robustly designed studies investigating periodontal disease and tooth losslink with cognitive health decline are required with a longer follow-up duration.

Ultrasound analysis of the masseter and anterior temporalis muscles in edentulous patients rehabilitated with full-arch fixed implant-supported prostheses

OBJECTIVES

Total tooth loss is common in the aging population resulting in insufficient chewing function with subsequent weakening of the masticatory muscles. The study aims to evaluate the changes in thicknesses of the masseter and anterior temporal muscle in edentulous patients following the reconstruction of implant-supported fixed prostheses and compare them with the dentate individuals.

MATERIALS AND METHODS

The study was designed as a prospective, single-center, controlled clinical trial. A total of 60 participants were included in the present study. The patients were divided into two groups; Group I (Test Group): 30 edentulous patients who received implant-supported fixed prostheses, Group II (Control Group): 30 dentate individuals of an age and sex-matched group. Ultrasonography was used to measure the cross-sectional thickness of the left and right musculus masseter and anterior temporalis immediately after the cementation of the prosthetic rehabilitation (T1), on the 1st (T2) and 6th (T3) months after rehabilitation and at a single time point in the control group.

RESULTS

The results showed that there were significant comparison differences in muscle thickness at the baseline measurements between groups while at the end of the 6th month, these differences were not significant. The muscle thicknesses of both the masseter and anterior temporalis muscles increased significantly at T2 and T3 compared to T1 in the test group. The asymmetry index between the left and right muscles in the test group and the asymmetry differences between groups also decreased significantly at the end of the 6th month.

CONCLUSION

The implant-supported fixed prostheses significantly increase the thicknesses of the masseter and anterior temporal muscle together with a decrease in the asymmetry between the left and right muscles. At six months, implant-treated patients showed similar muscle thicknesses compared to dentate individuals.

CLINICAL RELEVANCE

The findings suggest that implant-supported fixed prostheses can improve the masticatory function and facial symmetry of edentulous patients.

The predictive value of masticatory function for adverse health outcomes in older adults: a systematic review

Masticatory function is associated with a variety of health outcomes. The aim of this systematic review is to clarify the predictive value of masticatory function for adverse health outcomes, such as frailty, sarcopenia and malnutrition, in older adults. An online literature search covered articles published in English or Dutch in three databases (PubMed, Embase and CINAHL, last searched November 4th 2022). Inclusion criteria were: an observational study design, focus on adults aged ≥65 years and evaluation of the association between masticatory function and health outcomes. Reviews and articles published before the year 2000 were excluded. Methodological quality and risk of bias were assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies of the U.S. National Institutes of Health. Study population demographics, methods for assessing masticatory function, and the association between masticatory function and adverse health outcomes were extracted. From the 34 included studies, 5 studies had a prospective design, 2 had a retrospective design, and the other 27 studies had cross-sectional design. The majority of the studies were conducted in Japan (74%, n = 26). Twenty studies (59%) used one indicator for masticatory function, the other 41% used two (n = 9) or more (n = 5) indicators. Masticatory function was most frequently assessed with the maximum occlusal force (MOF) (79%, n = 27). The identified health outcomes were clustered into 6 categories: physical parameters and sarcopenia, history of falling, nutritional status, frailty, cognitive function and mortality. Despite the complex and multidimensional character of both masticatory function and most identified adverse health outcomes, some significant associations were reported. Prospective studies showed that reduced masticatory function in older adults is associated with incidence of frailty and frailty progression, cognitive decline and all-cause mortality. Regarding the other identified adverse health outcomes, i.e., physical measures and sarcopenia, history of falling and nutritional status, only cross-sectional studies were available and results were less concordant. As all prospective studies showed that reduced masticatory function in older adults is associated with adverse health outcomes, prevention of decline of masticatory function by adequate oral care may contribute to healthy ageing.

Muscle activity between dentate and edentulous patients rehabilitated with dental prostheses: A systematic review

BACKGROUND

Adequate muscle activity is important for the success of oral rehabilitation: it maintains the integrity of the stomatognathic system and is responsible for chewing movements needed to break, crush and grind food.

OBJECTIVE

To compare muscle activity using electromyography (EMG) while clenching or chewing soft and/or hard foods among individuals with natural dentition (ND) and edentulous patients rehabilitated with dental prostheses.

METHODS

This review was conducted until March, 2023, and the research question was "Is the muscle activity of edentulous patients rehabilitated with dental prostheses similar to that of dentate individuals?" A search strategy was conducted in PubMed/MEDLINE, The Cochrane Library, Web of Science, Lilacs, Embase and manual journal searches.

RESULTS

Ten studies were included in the analysis. Most of them reported that individuals with ND had significant higher muscle activity (clenching or chewing) than complete dentures (CD) users. However, no difference was observed between patients with full mouth implant-supported fixed dental prosthesis (ISFDP) and ND. Additionally, two studies compared patients with mandibular ISFDP with maxillary CD and individuals with ND and found no differences; however, one study concluded that patients with ISFDP with CD (maxillary or mandibular) had lower muscle activity than individuals with ND. Only one study reported a higher muscle activity in patients with full-mouth ISFDP than in individuals with ND.

CONCLUSIONS

Bimaxillary CD users had lower muscle activity than individuals with ND. During rehabilitation, the muscle activity of patients with full-mouth ISFDP and mandibular ISFDP with maxillary CD is similar to individuals with ND.

The effect of food supplements on completely edentulous women rehabilitated with complete dentures: A randomized controlled trial

Aim

Neglected oral health is a major issue, especially in women of developing countries, leading to early loss of teeth which may further lead to malnutrition, degradation of overall health, and increased chances of osteoporosis. Thus, the aim of this study was to assess the effect of food supplement on masticatory performance, nutritional status, electromyography (EMG) (masseter and temporalis), and bone mineral density (BMD) among women rehabilitated with complete denture.

Settings and Design

Hospital based randomized controlled trial.

Materials and Methods

A randomized controlled trial with 106 women of 45-65 years rehabilitated with complete denture (56 received food supplement and 50 did not receive food supplement) and 52 healthy control was conducted. The outcomes were assessed at baseline and 3 and 6 months of follow up (after complete denture fabrication). Outcomes were measured via masticatory performance, nutritional status (hemoglobin, serum calcium, albumin, and Vitamin D level), EMG of masseter and temporalis muscles, and BMD.

Statistical Analysis Used

Friedman's analysis of variance test was used as a nonparametric test, and the Statistical Package for the Social Sciences version 21.0 at a significance level of 0.05 was used for statistical analysis.

Results

A statistically significant change was observed during follow up for the group with food supplement for BMD, EMG, and masticatory performance. When biochemical parameters were assessed during follow up, no statistically significant change was observed for both groups (with and without food supplement), except for serum calcium level in group which received food supplement.

Conclusion

It was found that the magnitude of effect was remarkably meager in food supplement group which could be perhaps due to less time given for follow up period. Longer duration of trials would yield better results.

Electromyographic Evaluation of Muscle Activity in Patients Rehabilitated with Full Arch Fixed Implant-Supported Prostheses

Background and Objectives: Implant rehabilitation of complete edentulous arches has become more and more popular because of the increased access of the population to this type of treatment. Furthermore, the development of new rehabilitation procedures can be applied in most clinical cases, including in those with severe atrophy. Hence, this study aimed to assess the functional changes that can occur in the stomatognathic system after implant rehabilitation procedures. Materials and Methods: A total of 63 patients were accepted in the study. They were divided into a first control (dentate) group (CG) and a second study group (edentulous, SG). For the latter, 30 patients received 204 two-stage implants immediately loaded with provisional prostheses. Surface electromyography (EMG) was assessed at the time of prostheses fixation, while for some patients it was applied six months after the fixation of the fixed prostheses, as well. These supplemental investigated patients formed a third, follow-up study group (FSG). All assessments were performed during the processes of clenching and mastication. The obtained data of the two study groups, SG and FSG, were compared with those of the control group, CG. Results: No statistical differences were found in the electrical muscular activity between the study and control groups during both clenching and mastication (p > 0.05). In addition, there were no differences within the same study group, both initially and after 6 months. The only changes were noticed between static and dynamic values for the right masseter muscle in the follow-up group FSG (p = 0.008). Deviations of the overlapping coefficients were similar for all groups (p = 0.086): for CG, 20.5%, median 11.1 (min. 0, max. 104); for SG, 21.4%, median 12.2 (min. 0, max. 103); for FSG, 36.1%, median 26.9 (min. 0, max. 160). This revealed no neuromuscular adaption to the prostheses. Conclusions: Implant-prosthetic rehabilitation led to an EMG activity that was similar to that of dentate patients immediately after the placement of the fixed implant-supported prostheses. Moreover, the measured values did not change after six months of functioning for all evaluated parameters. This may point to an immediate restoration of the muscle contraction capacity, without the necessity of adaptation over time. The study serves as an argument for the application and reliability of the immediate fixed implant-supported prostheses from the perspective of muscle adaptation and functioning.

Clinical effectiveness of implant support for distal extension removable partial dentures: functional evaluation using occlusal force measurement and masticatory efficiency

BACKGROUND

Implant-supported removable partial dentures (ISRPD) are supported at the free-end region with implant retainers. As implant retainers prevent denture settlement and facilitate denture retention, this is intended to improve masticatory performance in comparison with that of conventional removable dentures. In the present study, we evaluated the effect of implant retainers at the free-end region of removable dentures on occlusal force and masticatory efficiency using a pressure-sensitive sheet, and measured glucose concentration in saliva after mastication with gummy candy.

METHODS

In the present study, the occlusal force and masticatory efficiency of 13 subjects were measured in the following three conditions: without dentures (Condition 1), wearing dentures but not supported by implants (Condition 2), and wearing dentures supported by implants (ISRPD) (Condition 3). All data were statistically compared.

RESULTS

Regarding the occlusal force, Condition 3 showed significantly higher scores than the other conditions; however, there were no significant differences between Conditions 1 and 2. Regarding the masticatory efficiency, Condition 3 showed significantly higher scores than Condition 2.

CONCLUSIONS

With ISRPD, the occlusal force and masticatory efficiency were increased in comparison with those with conventional removable dentures.

Patient-Centered Treatment Outcomes with Full-Arch PEEK Rehabilitation Supported on Four Immediate or Conventionally Loaded Implants. A Randomized Clinical Trial

This study aims to assess the treatment outcomes (functional and subjective) of full-arch fixed hybrid rehabilitations made of PEEK (poly-ether-ether-ketone) with milled crowns of nano-filled composite (NFC) supported on four to six implants. In this randomized clinical trial, 34 edentate patients in the upper and/or the lower jaws were treated with the fixed hybrid dentures. In 16 patients (47.1% of the sample), the implants were loaded immediately (IL) by means of a provisional fixed rehabilitation made of PMMA (polymethylmethacrylate) screwed on Multi-Unit (MU) abutments connected after emplacement of the implant; however, in the counterparts (n = 18) these MU abutments were covered by healing caps and were left unloaded during two months (conventional loading protocol—CL), when all patients received a fixed hybrid PEEK-NFC rehabilitation on the upper and/or the lower jaw. Treatment outcomes were assessed 12 months after prostheses delivery. Functional outcomes were calculated according to masticatory performance, estimated by mixing ability tests of two colored chewing gums after ten chewing strokes, by the occlusal force/area recorded by pressure-sensitive sheets, and by electromyography of masseters and temporal muscles at maximum biteforce. The subjective outcomes of the treatment were assessed using both the oral satisfaction scale (visual analog scale) and the Spanish version of the Oral Health Impact Profile (OHIP-20). The findings of the present study showed that treatment with fixed PEEK-NFC hybrid prostheses significantly improved the masticatory performance, bite force, occlusal pattern, quality of life, and satisfaction, with the IL group being those with significantly higher occlusal bite forces and greater satisfaction in comparison with CL group. It should be concluded that PEEK-NFC hybrid prostheses can improve several patient-centered outcomes and that loading protocol significantly affects the patient’s self-rated satisfaction.

The Thermal Influence of Oral Rehabilitation on the Cranio-Cervico-Mandibular Complex: A Thermographic Analysis

PURPOSE

Assess the thermal effect of prosthodontic treatment on the cranio-cervico-mandibular complex using infrared thermography.

METHODS

The treatment group was composed of adults of both sexes who underwent a prosthodontic treatment in which at least posterior occlusal contacts were added and/or the vertical dimension of occlusion was reestablished. The control group (CG) was constituted of adult subjects of both sexes, with no more than a single missing posterior tooth, excluding third molars. Thermograms were taken of the treatment group with a Flir i7 IR camera both before oral rehabilitation (TGB; n = 33) and two months after treatment was concluded (TGA; n = 19). CG (n = 33) had only one occasion for data acquisition.

RESULTS

Statistically significant differences were found when the thermal difference (ΔT) and the health status of the orbicularis oris muscle were compared between the TGB and the TGA groups (p = 0.020 and p = 0.003, respectively). By comparing the health status of the masseter muscle between the CG and TGB, statistically significant differences were also observed (p = 0.030).

CONCLUSION

A prosthodontic treatment appears to have a minimum or null effect on the ΔT and/or on the health status of the TMJ and the temporal muscle. In contrast, orbicularis oris muscles exhibited significant thermal variations.

Functional and Patient-Centered Treatment Outcomes with Mandibular Overdentures Retained by Two Immediate or Conventionally Loaded Implants: A Randomized Clinical Trial

This study aims to assess the treatment outcomes (functional and subjective) of mandibular overdentures retained on two implants with or without an immediate loading protocol. In this randomized clinical trial, twenty fully edentulous patients were treated with a mandibular two-implant-retained overdenture and a complete new maxillary denture. In half of the sample, the implants were loaded immediately by means of VulkanLoc^® abutments after emplacement of the implant, but in the counterparts, these VulkanLoc^® abutments were connected to implants two months after the surgery (conventional protocol), and until that time the dentures were retained by healing abutments. Treatment outcomes were assessed at two, six, and twelve months after surgery. Functional outcomes were calculated according to masticatory performance, estimated by the mixed fraction of a two-coloured chewing gum after five, ten, and fifteen chewing strokes, by the occlusal force recorded by pressure-sensitive sheets, and by the bioelectrical muscular activity. The subjective outcomes of the treatment were assessed using both the oral satisfaction scale (visual analogue scale) and the Spanish version of the Oral Health Impact Profile (OHIP-20). The findings of the present study show that new complete dentures resulted in significant improvements in chewing ability, patient satisfaction, and oral health-related quality of life and that subsequent implant-retained overdentures produced further and faster significant improvements. The loading protocol may influence those positive self-reported outcomes rather than the objective functional evaluations.

Effect of isometric exercises on the masseter muscle in older adults with missing dentition: a randomized controlled trial

Maintaining oral function in older individuals with missing teeth is important for leading a healthy and independent life. This study aimed to evaluate whether simple isometric exercises can maintain and improve the oral function [maximum occlusal force (MOF) and masticatory ability (MA)] and the masticatory muscle properties [masseter muscle thickness (MMT) and echo intensity (MMEI)] in older adults during the maintenance phase of removable prosthetic treatment. Participants were randomly categorized into the intervention and control groups. The mouthpieces were distributed, and participants were instructed to use them for exercising. The intervention group was instructed to perform maximum clenching for 10 s, whereas the control group was instructed to tap the teeth at an arbitrary speed for 10 s. Both were repeated five times at an interval of 5 s between each activity and twice daily for 4 weeks. The outcomes were measured after a month of exercise. The intervention group showed a significant improvement in the MOF, MMT during contraction, MMT at rest and MMEI during contraction. There were no significant differences in the MA and MMEI at rest. In the control group, no improvement was observed in any of the parameters. When the isometric exercises were performed using a mouthpiece, there was an improvement in the oral function and masseter muscle properties in older individuals with Eichner B status who used dentures.

Implant-supported overdenture with horizontal insertion for treating the edentulous atrophic maxilla: A case series

STATEMENT OF PROBLEM

Rehabilitation of edentulous patients with severe maxillary atrophy is a clinical challenge. Although several treatment options are available, the implant-supported overdenture has been widely advocated. However vertical insertion implant-supported overdentures have drawbacks, including wear, aging, and the continuous maintenance of retention systems. Whether an implant-supported overdenture with a horizontal insertion pathway can overcome these problems is unclear.

PURPOSE

The purpose of this observational study was to determine the clinical and biological behavior of a new type of implant-supported overdenture with a horizontal insertion pathway over a mean clinical follow-up period of 6 years.

MATERIAL AND METHODS

Ten study participants with an atrophic maxilla underwent rehabilitation with horizontal overdentures supported by 6 implants. Follow-up visits were scheduled at 3 months, 6 months, and annually thereafter. The variables analyzed were implant and prosthetic survival, peri-implant tissue behavior, mechanical complications, and patient satisfaction.

RESULTS

The follow-up period ranged from 5 to 8 years, mean ±standard deviation 6.3 ±1.2 years. A total of 60 implants and 10 horizontal overdentures were placed. The clinical survival of the implants was 98.3% (mean peri-implant bone loss, 1.3 ±0.4 mm) and was 80% of the prostheses. Overall, mean patient satisfaction as assessed with a visual analog scale was 7.4, with 8.5 for esthetics and 9.5 for function.

CONCLUSIONS

The horizontal implant-supported overdenture provided a functional alternative to conventional prostheses.

Masseter muscle activity of conventional denture, fixed prosthesis, and milled bar overdenture used for All-on-4 implant rehabilitation: A within-subject study

PURPOSE

to examine the electromyographic (EMG) activity of the masseter muscles in patients with conventional dentures and compare it to EMG activity of fixed prosthesis, and milled bar overdentures used to rehabilitate mandibular atrophied ridges according to the All-on-4 concept.

METHODS

Eighteen edentulous subjects with atrophied mandibles received complete dentures (CD, control). After 3 months, four implants were installed between the mental foramina according to the "All-on-4" protocol and loaded immediately. After osseointegration, fixed prostheses (FPD) or milled bar overdentures (MBO) were given to the patients in random order. Primary (amplitude), and secondary (chewing rate, time of the masticatory cycle, time of masticatory burst, and masticatory time) outcomes were evaluated 3 months after using CD, FPD, and MBO. The evaluations were made during mastication of carrot (hard) and cake (soft) foods.

RESULTS

FPD and MBO were associated with a significantly higher (amplitude, time of masticatory cycle, and time of masticatory burst), and significantly lower (chewing rate and masticatory time) compared with conventional dentures. Primary and secondary outcomes did not differ between FPD and MBO. Carrot had significantly higher amplitude, chewing rate, time of masticatory burst, and masticatory time than cake, while cake had a significantly higher time of masticatory cycle than carrot.

CONCLUSIONS

Within limitations of this study, milled bar overdentures for All-on-4 implant rehabilitation of atrophied mandible is not less efficient than fixed prostheses in terms of electromyographic activity of the masseter muscle. Both prostheses significantly improve muscle activity, chewing rate, time of masticatory cycle, time of masticatory burst, and masticatory time compared with conventional dentures.

Mandibular residual ridge morphology in relation to complete dentures and implant overdentures-Part I: Predictors for perceived conventional denture stability

BACKGROUND

There is lack of reliable predictors for success of conventional complete denture (CCD) therapy, which in turn might affect the effectiveness of subsequent implant-retained overdenture (IOD) therapy.

PURPOSE

To investigate relationships between digitally obtained geometrical mandibular residual ridge measures and perceived CCD-stability.

MATERIALS AND METHODS

30 CCD wearing patients (67.9 ± 7.0 years) for whom a new set of CCDs was advised, were treated with new CCDs. Digitalized mandibular gypsum models were measured using the Geomagic Studio 2013 software. Data were obtained for (1) height, width, and cross-section surface area of the residual ridge at different locations (midline, premolar, and anterior edge of retromolar pad) and (2) denture base surface area. Scatter plots and multivariate regression analyses were used to investigate associations between the geometric data and denture base surface area, and correlated with denture stability scores (Spearman rank test).

RESULTS

Scatter plots showed that best model fit for denture base surface area was mean ridge height (R² = 0.906). Multivariate regression showed that height at premolar location (p = 0.001) had largest effect on denture base surface area (R² = 0.796). Ridge morphology variables, except width at midline location, were significantly correlated with CCD-stability (p-values <0.05). CCD-stability was significantly correlated with denture base surface area (p ≤ 0.001).

CONCLUSION

Residual ridge height at premolar location was most predictive for denture base surface area and perceived CCD-stability.

Immediate or delayed loading protocols for two-implant mandibular overdentures: A systematic review and meta-analysis of randomized controlled trials

STATEMENT OF PROBLEM

The immediate loading protocol for 2-implant mandibular overdentures has been widely reported. Nevertheless, the clinical effects reported in different articles are quite different.

PURPOSE

The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to compare the clinical effects of immediate and delayed loading of 2-implant mandibular overdentures.

MATERIAL AND METHODS

The review followed the guidelines of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). PubMed, Cochrane Library, Web of Science, Embase, Scopus, ScienceDirect, CBM, CNKI, and Wan Fang databases were searched electronically for RCTs published before March 25, 2020. Two authors independently conducted literature screening, quality assessment, and data extraction. The outcomes of interest were implant failure rate, marginal bone loss (MBL), implant stability quotient (ISQ), periotest value (PTV), and patient satisfaction.

RESULTS

A total of 2498 unduplicated records were identified. After full-text analysis, 7 eligible RCTs were included. All studies were followed for at least 12 months, and the meta-analysis was based on this. The meta-analysis showed that the implant failure rate in the immediate group was higher than that in the delayed group, but there was no statistically significant difference (I²=0%; n=7; risk difference [RD]=0.03; 95% confidence interval [CI]=-0.01 to 0.08). The difference of MBL between immediate and delayed loading was not significant (I²=88%; n=6; mean difference [MD]=-0.04; 95% CI=-0.16 to 0.24). Because of the limited articles reporting on ISQ, PTV, and patient satisfaction, no quantitative analysis was conducted for these outcomes.

CONCLUSIONS

Although the implant failure rate was more likely to favor the delayed group, available evidence indicates no statistical difference in implant failure and marginal bone loss between immediate and delayed loading protocols.

Impact of implant superstructure type on oral health-related quality of life in edentulous patients

BACKGROUND

The effect of the type of implant superstructure on oral health-related quality of life (OHRQoL) among edentulous patients remains controversial.

PURPOSE

The purpose of this study is to investigate the association between the type of implant superstructure and OHRQoL.

MATERIALS AND METHODS

Seventy-two completely edentulous patients who received implant fixed complete dentures (IFCDs) or implant overdentures (IODs) were administered the Oral Health Impact Profile (OHIP) questionnaire during the post-treatment maintenance period. The OHIP summary score, as well as the four dimension scores, were calculated to evaluate OHRQoL.

RESULTS

The mean OHIP summary score for the IFCD group tended to be lower than that for the IOD group, but this difference was not statistically significant (19.9 ± 21.9, 22.8 ± 18.2, respectively; P = .57). However, a significant group difference was found in the four dimension scores (P < .01), with the OHIP item scores representing masticatory function being significantly lower in the IFCD group than in the IOD group (P < .05).

CONCLUSIONS

Our results suggested that patients with an IOD exhibited comparable OHRQoL to those with an IFCD, with the exception of perceived masticatory function.

Maxillary Implant-Supported Overdentures: Mechanical Behavior Comparing Individual Axial and Bar Retention Systems. A Cohort Study of Edentulous Patients

Background and objectives: To compare the medium- to long-term mechanical behavior of overdentures with two different retention systems: overdentures with Locator® axial retention, and vertical insertion overdentures with bar retention, used to rehabilitate edentulous maxillar. Material and Methods: This prospective study assessed patients presenting complete maxillary edentulism, rehabilitated by means of implant-supported overdentures (n = 20), 10 with Locator® axial retention (ODA group) and 10 with overdentures on bars (ODB group). Patients also completed a questionnaire to determine their satisfaction with treatment. Results: The mean follow-up time in both groups was 11.4 years, with follow-up times in both groups ranging from 5 to 14 years. The ODA group suffered mechanical complications such as retention loss, need for nylon retention insert changes, resin fracture, and need for relining. In the ODB group, prosthetic dental wear, screw loosening, and complete prosthetic failure were more common. A total of 19 implants failed (23.8%); of these, 11 were in the ODA group (failure rate = 27.5%) and eight in the ODB group (failure rate = 20%). The patient satisfaction questionnaire obtained a mean score of 7.9 out of 10 in the ODA group, and 9.75 in the ODB group. Conclusions: in rehabilitations of edentulous maxillar by means of implant-supported overdentures, both the systems assessed were shown to be effective in the medium to long term. Patients expressed a high level of satisfaction with the treatments received.

Does the natural maxillary dentition influence the survival rate of mandibular metal-resin implant-supported fixed complete dentures? A systematic review and meta-analysis

STATEMENT OF PROBLEM

Consensus is lacking regarding the influence of the maxillary dentition on the survival rate of a mandibular metal-resin implant-supported fixed complete denture (MRISFCD) with distal cantilevers.

PURPOSE

The purpose of this systematic review was to identify whether an opposing natural dentition influences the survival rate of mandibular MRISFCDs.

MATERIAL AND METHODS

A literature search was performed up to February 2018 from MEDLINE/PubMed, Scopus, Web of Science, Cochrane Library, BBO/LILACS databases and also in the non-peer-reviewed literature through Open Grey. Clinical studies regarding natural (ND), removable prostheses (RP), and complete fixed maxillary implant dentitions (ID) with at least a year of follow-up were included. The quality of the included studies was analyzed, and the risk of bias was reported. A meta-analysis comparing the survival rate of ND with RP and ND with ID was performed with a confidence interval (CI) of 95%, and heterogeneity was tested by an I² index. Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach was used to determine the certainty of the evidence.

RESULTS

From a total of 112 ND, 69 ID, and 204 RP in the maxillary dentition, the overall prevalence of failures was 5.4% (6/112; 95% CI [2.3 to 10.76]) for ND, 13.99% (20/69; 95% CI [0.77 to 39.41]) for ID, and 4.9% (10/204; 95% CI [0.69 to 12.18]) for RP. No statistical differences were detected in the success rates between ND and RP (risk difference = 0.00 [-0.06, 0.06]; P=.93; I²=27%) or between ND and ID (risk difference=0.00 [-0.06, 0.07]; P=.97; I²=0%), both with moderate evidence.

CONCLUSION

With a moderate certainty of evidence, it is suggested that natural maxillary dentitions do not affect the survival rate of mandibular MRISFCDs differently from other prosthetic designs.

Electromyographic Activity Changes of Jaw-Closing Muscles in Patients with Different Occlusion Schemes after Fixed Prosthetic Restoration

Background/Aim: To investigate the electromyographic (EMG) activity changes of jaw-closing muscles in patients with different occlusion schemes and posterior edentulous span, after the placement of teeth-supported fixed partial denture (FPD).

Material and Methods: The study sample consisted of 20 patients (10 men and 10 women, the mean age being 50 years) with a posterior edentulous area that includes two missing premolars or one premolar and one molar. The participants were divided into two groups with different occlusion schemes: canine-guided occlusion (CGO) and group function occlusion (GFO). The metal-ceramic FPD were fabricated according to the clinic-standardized protocol. EMG activities of masseter and anterior temporalis patients’ muscles were recorded with bipolar surface electrodes during maximal voluntary clenching. EMG evaluation was repeated twice: (T1) before the fabrication of FPD (T2) after eight weeks of FPD cementation and intraoral functioning of restoration. The data were subjected to Analysis of Variance–ANOVA within the methodological framework of the General Linear Models with Repeated Measures. The Bonferroni test was used to compare multiple mean measures. Statistical analysis was conducted with SPSS ver. 11.5. The level of significance was predefined at a=0.05.

Results: Group 1 with CGO presented significantly higher levels of masseter (mean maximum EMG average before 79.36μV and 139.68μV after) and temporalis (mean maximum EMG average before 79.07μV and 149.37μV after) EMG activity after FPD placement. Group 2 with GFO also showed significantly higher levels of masseter (mean maximum EMG average before 61.57μV and 165.30μV after) and temporalis (mean maximum EMG average before 56.94μV and 133.08μV after) EMG activity after the prosthetic restoration.

Conclusions: It may be concluded that fixed prosthetic restoration, in both patients with canine-guided and group function occlusion, results in increased EMG jaw-muscle activity.

Relationship of aging, skeletal muscle mass, and tooth loss with masseter muscle thickness

Background

Previous studies have reported a relationship between masseter muscle thickness and tooth loss or limb muscle thickness. However, it is not yet known whether masseter muscle thickness is related to appendicular skeletal muscle mass, and grip strength. The purpose of this study was to determine which of the two variables—tooth loss or appendicular skeletal muscle mass index—is more strongly related to masseter muscle thickness, and to identify a suitable indicator of decreasing masseter muscle thickness in healthy elderly individuals.

Methods

Grip strength, walking speed, body weight, skeletal muscle mass index, tooth loss, and masseter muscle thickness at rest and during contraction were determined in 97 community-dwelling elderly individuals aged ≥65 years (men: 44, women: 53). Masseter muscle thickness was chosen as the dependent variable, while age, skeletal muscle mass index, body weight, grip strength, and tooth loss were chosen as the independent variables. Multiple regression analysis was conducted using the stepwise regression method.

Results

In men, grip strength was the only independent predictor of masseter muscle thickness at rest. Tooth loss and grip strength were independent predictor of masseter muscle thickness during contraction. In women, tooth loss was the independent predictor of masseter muscle thickness both at rest and during contraction, while grip strength and body weight were the independent predictor of masseter muscle thickness at rest only.

Conclusions

We confirmed that in healthy elderly individuals, tooth loss has a stronger relationship with masseter muscle thickness than aging and skeletal muscle mass index do. Masseter muscle thickness in both elderly men and women is also associated with grip strength, suggesting that grip strength can be used as an indicator of masseter muscle thickness in this population.

Association between residual teeth number in later life and incidence of dementia: A systematic review and meta-analysis

Background

It has been suggested that tooth loss in later life might increase dementia incidence. The objective of this analysis is to systematically review the current evidence on the relationship between the number of remaining teeth and dementia occurrence in later life.

Methods

A search of multiple databases of scientific literature was conducted with relevant parameters for articles published up to March 25th, 2017. Multiple cohort studies that reported the incidence of dementia and residual teeth in later life were found with observation periods ranging from 2.4 to 32 years. Random-effects pooled odds ratios (OR) and 95% confidence intervals (CI) were estimated to examine whether high residual tooth number in later life was associated with a decreased risk of dementia. Heterogeneity was measured by I². The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used to assess the overall quality of evidence.

Results

The literature search initially yielded 419 articles and 11 studies (aged 52 to 75 at study enrollment, n = 28,894) were finally included for analysis. Compared to the low residual teeth number group, the high residual teeth number group was associated with a decreased risk of dementia by approximately 50% (pooled OR = 0.483; 95% CI 0.315 to 0.740; p < 0.001; I² = 92.421%). The overall quality of evidence, however, was rated as very low.

Conclusion

Despite limited scientific strength, the current meta-analysis reported that a higher number of residual teeth was associated with having a lower risk of dementia occurrence in later life.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0729-z) contains supplementary material, which is available to authorized users.