Implant-supported Overdentures Research Articles

An Innovative Meta-Systematic Review into the Landscape of Literature and the Concluding Evidence on the Quality of Life of Patients Using Two Implant Supported Mandibular Complete Denture Prosthesis

Aim: The aim of this systematic review is to analyze the existing evidence on the quality of life of patients completely edentulous in the mandible. Materials and Methods: A search questionnaire was formulated using population intervention comparison outcome (PICO) analysis, and a comprehensive search was initiated in PubMed Central, Medline, Cochrane, and Google Scholar databases for the related topics. Manuscripts published till December 2019 were included in this review. Out of the 63 articles obtained from searching all databases, 27 studies were excluded based on the title and abstract. Out of the remaining 36 studies, 12 were excluded based on the inclusion and exclusion criteria of our interest and 24 were included on the basis of core data. Results: One review author identified randomized trials meeting inclusion criteria for this review. Two review authors extracted data and assessed study quality. The oral health-related quality of life in completely edentulous mandibular patients wearing implant-supported overdentures was better when compared to conventional tissue-supported complete denture, and a minimum two implant-supported mandibular complete denture has sufficient improvement in oral health-related quality of life. Conclusion: There are about more than 170 reviews and clinical trials that have been published in support of the same for the past two decades. Thus, the clinicians may not be tempted in placing additional implants in well-formed mandibular edentulous ridges. To enhance the understanding of mandibular implant overdenture treatment, clinicians must scrutinize the existing evidence and formulate a protocol by striking a balance between efficient and evidence based treatment.

Comparison of Three Types of Stud Attachments on Retention and Strain Energy in the Mandibular Implant-Supported Overdentures

Background: The present in vitro study assessed he effects of three different Stud attachments on the retention and strain energy in the mandibular implant-supported overdentures.
 Methods: Two parallel implants (Implantium System) were placed on the mandibular canines’ regions and a chrome-cobalt casting framework was prepared as the denture base. The implant fixtures were installed on the canine location and the pulling was performed by three orthodontic wires in the Instron machine with a speed of 0.5 min/mm. Dislodging forces were applied to the housings in two vertical and oblique directions on three different Stud attachments (Ball, Kerator, Positioner). All three wires were connected to the device in the vertical position while one wire was separated from the molar’s region in the oblique loadings. The retention of these three attachments was statistically analyzed by means of one-way analysis of variance.
 Results: Significant differences were found between the attachments (F (2, 15) =33.01, p<0.0001). Furthermore, Retention forces in the oblique loadings were significant differences between the attachments (F(2,15)=175.10, p<0.0001). The effect size, calculated using eta squared, was 0.95, which is considered large. The strain energy was 4.08, 3.05 and 1.04 J for the Ball, Positioner and Kerator attachments in the vertical loadings and 4.05, 1.44 and 3.07 J in the oblique loading respectively.
 Conclusion: The retentive forces and strain energy of ball attachments were greatest than other studied attachments in the vertical and oblique loadings.

Immediate vs Conventional Loading of Mandibular Overdentures: A Comprehensive Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Clinicians treating overdenture patients need to know if immediate loading and conventional loading results in similar outcomes. This study aimed to perform a systematic literature search of studies comparing immediate and conventional loading of mandibular overdentures irrespective of the number of implants and conduct a meta-analysis of implant failure and marginal bone loss (MBL). A literature search of PubMed, ScienceDirect, Ovoid, Springer, and Google Scholar databases was performed for randomized controlled trials (RCTs) comparing immediate vs conventional loading of mandibular overdentures. The primary outcome was implant failure and the secondary outcome was marginal bine loss (MBL). A descriptive analysis was performed for other outcomes. Thirteen trials were included. Only one trial compared the immediate and delayed loading of single implant-supported overdenture. Seven trials used 2 implants, 1 trial used 3 implants while 4 trials used 4 implants. Meta-analysis indicated no statistically significant difference in implant failure and MBL between immediate and conventional loading of 2- and 4-implant supported overdentures. Descriptive analysis indicated no difference in peri-implant tissue indices, implant stability, and quality of life outcomes between the 2 loading protocols. There may be no difference in implant failure and MBL with immediate loading or conventional loading of 2- and 4-implant supported mandibular overdentures. Literature review indicates that there may be no difference in peri-implant tissue indices, implant stability, and quality of life outcomes between the 2 loading protocols. The overall quality of evidence is moderate. Further, adequately powered RCTs are required to strengthen the evidence.

Peri-implant mucosal response to implant-supported overdentures: A systematic review and meta-analysis.

To systematically review and evaluate the effects of different types of attachments, implant numbers and loading protocols on the peri-implant mucosa of implant-supported overdentures (ISODs). The impact of peri-implant tissue health on the ISOD treatment outcome is unclear, and current evidence is inadequate on this aspect. A systematic literature search for randomised controlled trials or prospective studies was conducted in indexed databases from 1995 to April 2020. The focused question was as follows: How does the peri-implant mucosa respond to implant-supported or implant-tissue-supported complete overdentures based on different types of attachments, implant numbers, and loading protocols, in terms of clinical outcomes achieved [plaque index (PI), gingival index (GI), probing pocket depth (PD) and bleeding index (BI)]? A random- or fixed-effects model was applied to measure the significance of standardised mean differences (SMD) of PD between the groups. Seventeen studies met the eligibility criteria. The SMD for PD between splinted/bar and unsplinted/stud attachments was 0.10mm (95% CI: -0.27 to 0.47; P=.60) and between 2- and 4-implant groups was 0.15mm (95% CI: -0.16 to 0.45; P=.34), which were not statistically significant. Significant difference (P=.003) was observed between immediate/early loading and delayed loading (SMD=0.46mm [95% CI: 0.16 to 0.75]). Probing depth for the immediate loaded implants was significantly higher than for the delayed loading group. No attachment type, implant number or loading protocol seemed to have a clear advantage over the other, in terms of other peri-implant mucosal outcome measures.

Midline denture base strains of glass fiber-reinforced single implant-supported overdentures

Statement of problemThe fracture incidence of implant-supported overdentures is more frequent in the area of attachment because of stress concentration and denture deformation in this area. How E-glass fiber reinforcement can address this problem is unclear. PurposeThe purpose of this in vitro study was to evaluate the influence of unidirectional E-glass fiber reinforcement on the mid-line denture base strains of single implant-supported overdentures. Material and methodsAn experimental acrylic resin cast was constructed with a single implant placed in the mid-line area and a ball attachment screwed to the implant. Twenty-four experimental overdentures were constructed and divided into 4 groups: group AP fabricated from autopolymerizing acrylic resin without fiber reinforcement, group APF fabricated from autopolymerizing acrylic resin with unidirectional E-glass fiber reinforcement running over the residual ridge and the ball matrix, group HP fabricated from heat-polymerized acrylic resin without fiber reinforcement, and group HPF fabricated from heat-polymerized acrylic resin with unidirectional E-glass fiber reinforcement running over the residual ridge and the ball matrix. A biaxial rosette strain gauge was attached to the incisor areas of each overdenture above the attachment level (Ch1, Ch2) and to a multichannel digital strain meter. A static vertical load of 100 N was applied to the first molar area bilaterally by using a universal testing device during strain measurement procedures. The differences in the mean strain and deflection values among the investigated groups were evaluated for statistical significance using 1-way analysis of variance (ANOVA) with the Tukey post hoc multiple comparison (α=.05). ResultsThe type of acrylic resin did not have a statistically significant effect on the mean strain values among groups (P=.350), while the reinforcement did significantly affect them (P<.001). The interaction between reinforcement and acrylic resin was not statistically significant (P=.552). Both strain gauge channels in group APF and group HPF recorded significantly lower strain values by almost 50% than those of group AP and group HP (P<.05). ConclusionsUnidirectional E-glass fiber reinforcement placed over the residual ridge and implant attachment significantly reduced denture base strains and deformation of single implant-supported overdentures.

Two Years after Loading Performance of Implant-Supported Overdenture with Metal Bar and Low-Profile Attachments: A Prospective Case Series Multicenter Clinical Study

Background. Prosthetic rehabilitation of patients with atrophic arches can be very challenging. Purpose. The aim of the present prospective multicenter study was to report the two-year preliminary data on clinical and radiographic performance of implant-supported overdentures with a metal bar and low-profile attachments. Material and Methods. A computer-aided design/computer-aided manufacturing (CAD/CAM) titanium bar or a conventional cast metal bar was fabricated according to the anatomy of the ridge, prosthetic contours (teeth setup), and implant position. Three to six threadable OT Equator attachments (Rhein 83, Bologna, Italy) were placed along the implant bar. A cobalt-chromium alloy metal framework was fabricated and fitted onto the metal bar as a counterpart. Prosthetic survival rate, biologic and technical complications, peri-implant bone loss, changes in oral health impact profile index, bleeding on probing, and plaque index were reported. Results. Overall, 177 implants were placed (range three to six) to support 43 metal bars with 170 OT Equators (Rhein 83, range three to six). Eleven metal bars were fabricated using CAD/CAM technology, while the other 32 were conventionally produced using cast technique. All the participants were followed up for at least two years (mean 42.2 months, range 24–88 months) after prosthesis delivery. Two maxillary implants failed in one nonsmoking patient (1.1%). The 2-year prosthesis survival rate was 97.7%. Only three minor technical complications were reported. Two years after loading, the mean marginal bone loss was 0.22 ± 0.09 mm (95% CI: 0.16 to 0.26). Two years after loading, OHIP was 22.3 ± 7.1 (95% CI from 17.4 to 24.6). Compared to the baseline, the difference was statistically significant ( P ≤ 0.001 ). At the two-year follow-up session, successful periodontal parameters were experienced. Conclusions. Implant overdenture supported by a CAD/CAM titanium bar may be a reliable option for the treatment of the edentulous arch over a 2-year period. Oral health-related quality of life significantly improved in all treated participants.

Ability to adjust occlusal force in implant-supported overdenture wearers.

The purpose of this study was to evaluate the occlusal force adjusting ability of implant-supported overdenture (IOD) wearers, as compared with natural teeth and complete dentures. Subjects were those with natural dentition (ND group; 19 subjects), those with implant-supported overdentures (IOD group; 7 subjects), and those with complete dentures (CD group; 14 subjects). Subjects were asked to hold test foods (peanuts and biscuits mounted on a custom-made apparatus with a force transducer) between their anterior incisors (hold phase) and split test foods (split phase). The mean value of the occlusal force during the hold phase (hold force), the peak force rate during the split phase (peak force rate), the time required to split test foods (duration), and the maximum occlusal force in the split phase (split force) were selected as outcomes. Data were analyzed with Wilcoxon's signed rank test, the Kruskal-Wallis test, and multiple regression analysis (Statistical significance levels: 5%). For peanuts, the peak force rate for the ND group was significantly higher than the IOD and CD groups. The duration of the CD group was significantly longer than the ND and IOD groups. Multiple regression analysis indicated that even with adjustment for age and sex, there were significant differences in the peak force rate between the ND and the IOD, CD groups, and in the duration between the ND and CD group. Subjects with IODs showed superior ability to adjust occlusal force, as compared with complete dentures, although it didn't match the natural dentition.

Observation of the effect on immediate mandibular implant-supported overdenture of micro implant system of Italy

The study was design to investigate the clinical effect of Micro implant system in Italy on immediate mandibular implant-supported overdenture. A total of 192 patients with mandibular edentulous treated in our hospital were randomly divided into 2 groups in which the control group consisted of 96 patients treated with immediate mandibular implant-supported overdenture by Xive implant system, while the observation group included 96 cases treated with the overdenture by Italy Micro implant system. Patients were followed up for 1 year and then the states of implant-borne overdentures, marginal bone resorption around alveolar bone, the compatibility of implant restorations with adjacent teeth, adverse events and satisfaction degree were compared between the groups. According to the results of 1-year follow-up, the resorption around alveolar bone of the observation group was significantly higher than that of the control group (p&lt;0.05). In the observation group the differences in labial gingival margin position, gingival color and texture were significantly better (p&lt;0.05) as compared to control group. The incidence of adverse events was notably lower (p&lt;0.05). The Italy Micro implant system has significant curative effect on mandibular implant-supported overdentures with good compatibility of the implant restorations with adjacent teeth and low incidence rate of adverse reactions, so it is worthy of clinical application and spreading.

A 5-Year Retrospective Study Evaluating Periodontal Health and Oral Health-Related Quality of Life of Implant-Supported Overdentures With Locator and Magnetic Attachments.

This study compared peri-implant vertical bone loss, the periodontal index, prosthodontic maintenance requirements and oral health-related quality of life (OHQoL) of patients using mandibular implant-supported overdentures with 2 different attachment systems after an average of 5 years of use. Sixteen mandibular overdenture patients with magnet attachments (group 3), 24 with implant-supported mandibular overdentures with Locator attachments (group 2), and 25 conventional complete denture patients (group 1) were included in the study. The existing at least 5 years old dentures of all patients were evaluated for prosthodontic maintenance by the same prosthodontist and the patients were administered the oral health impact profile-14-Turkish version (OHIP-TR-14) questionnaire. Peri-implant tissue health was evaluated clinically in terms of plaque scores, bleeding scores, probing depth, and gingival index. Radiographic evaluation was performed in terms of peri-implant vertical bone loss. Radiographic evaluations were performed 5 years after overdenture insertion. There were no statistically significant differences between the groups in terms of total OHIP-TR-14 scores (P > .05). Although the average vertical bone resorption measured in group 2 at the end of 5 years was 1.38 mm, there was an average vertical bone loss of 1.45 mm in group 3, but this difference was not statistically significant (P > .05). Among the periodontal health indicators, there were no statistically significant differences in the mean values for periodontal indexes. According to results of the study, there were no differences in peri-implant vertical bone loss in groups 2 and 3, in periodontal health in mandibular overdentures with groups 2 and 3, or between total OHIP-TR-14 scores of patients in all groups.

Evaluation of complications in implant-supported locator retained removable dentures: 24 Months Retrospective Study

Aim: The purpose is to evaluate the complications that occur in implanted locator supported removable dentures for 2 years clinically and radiologically.Materials and methods: Study between the years of 2014-2019, was performed on 121 patients who underwent 284 dental implants and came to their controls at the 12th and 24th months. Patients included in the retrospective study were 52 men and 69 women. Complications detected in the first 24 months after the implant supported prosthesis applied; relining and rebasing, loss of retention (housing removal, wear of the retaining clip) and fracture in the base of prosthesis were recorded and evaluated. Data were analyzed using One‐way ANOVA and Tukey's HSD tests. A P value of &amp;lt; 0.05 was considered statistically significant.Results: In implant-supported removable prostheses, there are significant differences were found between the increasing complication rates at 12th and 24th months (p &amp;lt;0.05). The most common complication at the end of 24th month in overdenture prosthesis with implant supported locator holder applied to the maxilla and mandible, respectively; relining of prosthesis (11.57%), rebasing of prosthesis (6.6%), loss of retention (5.79%) and prosthetic base fracture (4.13%).Conclusion: Based on the data analyzed in our study, removable prostheses showed different types and frequency of complications. Treatment of implant-supported overdenture prostheses, routine control of the prostheses is important.

Oral Health Related Quality of Life of Patients Using Conventional Dentures versus Implant-Supported Overdentures.

Objectives:This study aimed to compare the oral health related quality of life (OHRQoL) of patients using conventional dentures versus implant-supported overdentures.Materials and Methods:This study evaluated the OHRQoL of 90 patients between 35 to 75 years who were selected from several public and private dental clinics in Tehran in 2018. Of all, 45 had conventional dentures of both jaws, and 45 had a mandibular overdenture supported by two implants at the site of mandibular canine teeth and a conventional maxillary denture. The OHRQoL of patients was determined using the Oral Health Impact Prfile-20 (OHIP-20). The questionnaire was translated to Persian, and its content validity and internal consistency were confirmed. Data were analyzed by one-way ANOVA, Mann-Whitney test, and independent t-test.Results:In the conventional denture group, 46.7% had good, 46.7% had moderate, and 6.6% had poor OHRQoL. These values were 55.6%, 37.8% and 6.6% in the overdenture group, respectively. Level of education had a significant correlation with the total score of OHIP-20 in both groups (P<0.05). But no significant association was noted between the residential status and gender of patients with different domains of OHRQoL (P>0.05) except for the psychological disability domain, which had a higher mean value in males with conventional dentures (P<0.05).Conclusion:Patients with a mandibular overdenture supported by two implants at the site of canine teeth and a conventional maxillary denture had higher OHRQoL than patients with conventional dentures of both jaws.

Retreatment of multiple failing maxillary implants after full arch rehabilitation: a retrospective, observational cohort study

The aim of this study was to assess implant retreatment in a group of patients whose maxillary implants were all failing after full arch rehabilitation. Treatment involved implant removal, augmentation, and placement of an overdenture supported by four to six implants. All consecutive patients referred between 2008 and 2018, following multiple late implant failures in the rehabilitated maxilla, were included in the study. Seventy implants in 15 patients were evaluated at 3.3 ± 2.5 years (range 1.1–8.6 years) after loading. Implant survival, complications, clinical parameters, marginal bone loss, and patient-related outcome measures were recorded at the time of evaluation. Overall implant survival was 95.7%. Three implant failures occurred within the first year of function. Marginal bone loss was 0.32 ± 0.46 mm; pocket probing depth was 4.55 ± 1.59 mm. Plaque, calculus, inflammation, and bleeding were hardly seen (median index score 0). Patients scored their satisfaction with their overdentures as high (mean overall score 8.7 ± 1.2, maximum 10). Chewing soft and tough food was scored as ‘good’ and hard food as ‘moderate’. The mean Oral Health Impact Profile score was 29.5 ± 33.3. It can be concluded that the replacement of multiple failing implants in an edentulous maxilla after bone augmentation is a safe and predictable treatment procedure when applied as an implant-supported overdenture.

A Finite Element Analysis on Stress Distribution in Overdenture Implants and Implant Abutment Interface Using Different Attachment Systems: An In Vitro Study

Abstract Introduction The overdenture is an alternative to fixed implant-supported prosthesis for its relatively low-cost and in clinical cases where it is impossible to place multiple implants with appropriate number and arrangement in the arch to support a fixed prosthesis. In implant-supported overdentures, many attachments such as bars, ball, and magnets can be used. The anchorage system affects the retention and stability of the overdenture as well as the load transfer to the implant and the bone. The purpose of this study was to evaluate the exerted stresses on implants and implant–abutment interface by comparing different attachment systems used for implant-supported maxillary and mandibular overdentures using finite-element analysis. Materials and Methods Stress distribution in five different models with different attachments were evaluated using finite-element analysis. The studied attachment systems were Ball/O-ring and bar-clip attachments. Three models in mandible were studied, two implants with ball attachments, two implants with bar, and four implants connected with a bar. In maxilla, two models were studied, four implants with ball attachments, and four implants connected with bar. Forces were applied bilaterally on each model in the canine and molar region separately. The forces applied were 35N axially, 70N obliquely, and 10N horizontally. Results The ball attachments models showed the highest amount of stresses on the bone and on the implants in maxilla and mandible. The bar-clip attachment with four implants showed least stress in maxilla as well as in the mandible. The bar on four implants has better stress distribution as compared with the bar on the two implants.

A COMPARATIVE STUDY TO EVALUATE THE RETENTION OF CONVENTIONAL AND CAD/CAM FABRICATED BAR ATTACHMENT IMPLANT SUPPORTED ASSEMBLY (IN VITRO STUDY)

Introduction: The use of implant-supported overdentures is a common approach for treating edentulous mandibles. Retention and stability are provided through attachments; bar attachments being probably the most retentive due to greater mechanical stability and better wear resistance. Micro and macro movement between the retentive surfaces of an attachment during mastication, insertion and removal will lead to wear and decrease of the retentive capacity. Using CAD/CAM technology should produce more precise frameworks with better retention. Objectives: was to compare the retention of different Cobalt Chromium bar attachments fabricated by CAD/CAM technology and conventional methods. Materials and methods: Two bar attachments of different method of fabrication were studied. The bars were divided into two different groups according to whether the bar was fabricated using the conventional method or CAD/CAM technology. The retention provided by each bar was tested using Universal testing machine. The difference in retention was compared between the groups. Results:Data was collected, tabulated and statistically analyzed using the appropriate test. Group 1 needed 32.91N dislodging force. Group 2 needed 62.8N to separate the clip from the bar Conclusions: CAD/CAM fabricated bars showed a significantly higher retentive force in comparison to conventional bars.

Comparison of stress induced in mandible around an implant-supported overdenture with locator attachment and telescopic crowns – a finite element analysis

IntroductionOne of the principle factors for the success of implant supported/retained overdentures (IOs) is the manner in which the stresses are transferred to the surrounding bone. Hence, the aim of the present study is to compare the stress induced in the mandible around IOs, using two different attachment systems, locator and telescopic.Methods3D finite element models were prepared using Pro/ENGINEER or PTC Creo to simulate 4 clinical situations: IOs using two different attachment systems, locator and telescopic, with and without splinting. A vertical compressive load of 35N was directed toward the central fossa in the molar region of each overdenture. Non-linear static contact analysis was carried out to determine the stress distribution in various components of IOs. Then, the models were analyzed by a finite element program ABAQUS, and displayed using Von Mises stress patterns.ResultsThe contact stress values developed on the implant and attachment components were lower with locator attachment, in both splinted and non-splinted models. On the other hand, the stress distribution to the cortical bone was more with non-splinted/splinted locator attachments (3.73/4.12 Mega Pascals) when compared to the non-splinted/splinted telescopic attachments (2.66/3.7 Mega Pascals). The stresses in all the components of overdenture were greater with the splinted model compared to non-splinted, in both the attachment systems.ConclusionThe locator attachment might demonstrate superior clinical performance, as the stresses on implant and attachment components were less compared to telescopic. Non-splinted model showed better results in both the attachment types.

A 10-Year Follow-up of Rehabilitation of Severely Atrophied Edentulous Mandible with Implant Supported Over Denture: A Case Report

Background: Retention and support for the conventional complete dentures primarily dependent upon theresidual alveolar ridge and mucosa. Patients with poor mandibular ridge foundation usually suffer frominadequate denture retention and stability. In such cases, implant-supported overdenture treatment providesimproved prosthesis retention and support and thus greatly increasing patient’s acceptance toward prosthesisas when compared to conventional dentures.Case Report: The present case report describes a successful rehabilitation of resorbed mandibular ridgewith an overdenture supported by two implants and 10 years of follow-up was performed and discussed.Conclusion: Implant-supported overdenture provides a strong return for the investment in treatment time andexpense. The clinical outcome of this treatment is significantly better than that achieved with conventionalmandibular dentures, especially when patients are experiencing technical problems because of compromisedprosthesis retention and stability.

Bone Loss in the Posterior Edentulous Mandible with Implant-Supported Overdentures vs Complete Dentures: A Systematic Review and Meta-Analysis.

To analyze the current evidence on bone loss in the posterior edentulous mandible restored with complete dentures (CDs), two-implant-supported overdentures (2-IODs), or four-implant-supported overdentures (4-IODs). A search was conducted in the Ovid MEDLINE, Embase, Web of Science, CINAHL, and Cochrane databases for clinical studies comparing bone loss in posterior edentulous mandibles restored with CDs, 2-IODs, or 4-IODs. A meta-analysis was performed using statistical software to estimate the mean differences in bone loss with 95% CI. The level of significance was set at P < .05. The search strategy identified 2,806 articles, of which 14 met the inclusion criteria. The meta-analysis included 7 two-arm studies comparing CDs vs 2-IODs or 2-IODs vs 4-IODs. No statistically significant difference was found in bone loss between 2-IODs and CDs (mean difference -0.25 [95% CI -0.85 to 0.36]; P = .43), whereas bone loss was significantly lower with 4-IODs than with 2-IODs (mean difference -0.96 [95% CI -1.86 to -0.06]; P = .04). Overall, the data were highly heterogenous (I2 > 74%). 4-IODs can benefit the patient by decreasing bone loss in the posterior edentulous mandible. However, 2-IODs may not be superior to CDs in reducing bone loss in the posterior mandible. A validation of these results is needed through well-designed RCTs.

How many implants are necessary to stabilise an implant-supported maxillary overdenture?

Data sources Pubmed and EMBASE databases were searched from 2000 to 2017 and complemented by manual searching of the references of reviews and the full-text articles assessed for inclusion.Study selection The inclusion criteria were: (i) Randomised clinical trials (RCT), prospective or retrospective studies, and case series or case reports including at least ten totally edentulous patients rehabilitated with maxillary implant-supported overdenture; (ii) analysed one of the following outcomes: survival rate of the implants, survival rate of the overdenture and patient-reported results; (iii) had at least two years of follow-up; (iv) and were written in English language.Data extraction and synthesis The data extraction was performed by two independent reviewers. The comparison of the analysed outcomes was performed by nonparametric Fisher Test for unpaired data according to the number of implants and to the splinting technique. A meta-analysis was performed for the odds ratio (OR) for implant failure between four splinted implants and more than four splinted implants.Results Twenty-eight studies were included in the systematic review. The survival rate of implants appeared to be higher when at least four implants were placed to support the overdenture, compared to less than four implants. The survival rate of overdentures and the patient satisfaction were not influenced by the number of implants.The metanalysis could only be performed to compare the implant survival rate of a four splinted implants group and more than 4 splinted implants group, without significant differences between both groups (OR = 0.39; 95 % CI: 0.14, 1.14; p = 0.09).Conclusions Although the placement of at least four implants to support a maxillary overdenture seems to report higher implant survival rates, further studies are needed to confirm this conclusion. No differences were found for overdenture survival rates or patient satisfaction according to the number of implants.

Assessment of masticatory function of mandibular implant-supported overdenture wearers: A 3-year prospective study

Statement of problemWearers of mandibular complete dentures (CDs) often complain of retention and stability problems resulting in poor masticatory function. Evidence suggests that a mandibular overdenture (MOD) stabilized by 2 implants represents the treatment of choice to improve stability and masticatory function. Measurements are needed of the improvement in masticatory function after providing mandibular implant-stabilized overdentures. PurposeThe purpose of this prospective clinical study was to evaluate the changes in masticatory function from baseline (T0) to 3 months (T1) and 3 years (T2) in participants with MODs and to assess the effect of baseline mandibular bone height and volume on masticatory function after 3 years. Material and methodsParticipants were assessed for masticatory function by using masticatory performance involving paraffin wax cubes as an objective measure and by using masticatory ability involving a questionnaire as a subjective measure. Edentulous individuals presenting for replacement dentures were provided with conventional mucosa-supported prostheses and evaluated for masticatory function after a 3-month settling-in period (baseline measure). Before implant placement, baseline measures of bone height and volume were recorded from cone beam computed tomography (CBCT) images. The prostheses were then converted to implant-stabilized mandibular overdentures while any maxillary prostheses remained supported by the mucosa. Masticatory function was reassessed at 3 months and 3 years after insertion of the mandibular overdentures, and the mean changes from baseline were analyzed with the Wilcoxon signed-rank test. The effect of variables on masticatory function was determined by using multivariate linear regression analyses. ResultsA total of 23 participants were included in the study, with only 1 participant not completing the 3-year assessment. Significant improvement was observed in the masticatory performance (mixing ability index) (P<.01) and masticatory ability score (P<.001) from baseline to 3 months and baseline to 3 years. Bone height and volume had no significant effect on the improvement of masticatory function after conversion to an implant-stabilized mandibular overdenture. ConclusionsMasticatory function significantly improved after 3 months and was maintained over 3 years in participants with implant-stabilized mandibular overdentures. However, baseline bone height and volume had no significant effect on these changes in masticatory function after 3 years

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.