CAD/CAM versus traditional complete dentures: A systematic review and meta-analysis of patient- and clinician-reported outcomes and costs

STATEMENT OF PROBLEM

Computer-aided design and manufacturing (CAD/CAM) have been increasingly used to enhance the patient and clinician experiences with removable complete dentures (CDs). Yet, evidence from systematic reviews is lacking to validate the clinical significance of these digital prostheses.

PURPOSE

The purpose of this systematic review was to compare CAD/CAM CDs with the traditional ones in terms of patient and clinician-reported outcomes, post-insertion adjustment visits and costs.

MATERIALS AND METHODS

An electronic search of four databases [Medline (Ovid), Embase, Scopus and Cochrane CENTRAL; last update: May 2022] was performed to retrieve clinical studies comparing CAD/CAM and traditional CDs. Two independent reviewers screened the articles, extracted data (methods and outcomes) and assessed risk of bias of the included studies. The following outcomes underwent meta-analysis (random-effects model): overall patient and clinician satisfaction, oral health-related quality of life (OHRQoL), number of post-insertion adjustment visits, as well as laboratory and total costs.

RESULTS

This review included 11 studies. Meta-analysis revealed that CAD/CAM CDs are comparable to the traditional CDs in terms of overall patient satisfaction and OHRQoL. Clinician-reported data depended on the manufacturing technique: whereas milled CDs performed better than traditional CDs in terms of clinician satisfaction and number of adjustments, 3D printed and traditional CDs were similar. Fabrication of CAD/CAM CDs required significantly less laboratory and overall costs than the traditional CDs.

CONCLUSIONS

There is some evidence showing that CAD/CAM CDs are at least comparable to traditional CDs. Further well-designed randomized clinical trials are needed to evaluate the performance of specific CAD/CAM approaches for manufacturing CDs, however.

Patient-reported outcome measures and prosthetic events in implant-supported mandibular overdenture patients after immediate versus delayed loading: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Immediately loaded mandibular overdentures are clinically acceptable treatment options that have gained popularity because their use shortens the treatment duration. However, whether the immediate loading of dental implants can match the prosthetic events, satisfaction, and quality of life of delayed loading is still unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare the prosthetic events, satisfaction, and quality of life of immediate versus delayed loading implants in patients rehabilitated with mandibular overdentures.

MATERIAL AND METHODS

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered at The International Prospective Register of Systematic Reviews (PROSPERO) (CRD42021258187). Electronic searches were carried out by 2 independent reviewers in the PubMed/MEDLINE, Cochrane Library, and Web of Science databases up to May 2021. Only randomized clinical trials and prospective studies with at least 10 participants that compared immediate versus delayed loading were selected. A meta-analysis was performed by using the RevMan 5 software program for complications and maintenance outcomes.

RESULTS

Seven articles were included in the qualitative analysis, and 4 were included in the quantitative analysis. The meta-analysis demonstrated no significant difference between immediate and delayed loading for prosthetic complications (RR=1.71; 95% CI=0.67-4.37; I2=85%, P=.27) or maintenance (RR=1.92, 95% CI=0.44-8.28; I2=94%, P=.38).

CONCLUSIONS

Although the prosthetic complications and maintenance were more likely to favor the delayed loading group, available evidence showed no statistical difference for prosthetic complications and maintenance between immediate loading and delayed loading in mandibular overdentures.

3D printing vs traditional workflow for the fabrication of mandibular implant overdentures: study protocol for a mixed-methods cross-over RCT

BACKGROUND

Complete tooth loss is a significant global oral health issue, particularly impacting older individuals with lower socioeconomic status. Computer-assisted technologies enhance oral healthcare access by the elderly. Despite promising in vitro reports on digital denture materials, evidence from randomized clinical trials (RCTs) is lacking to verify their performance. This cross-over RCT will investigate whether 3D-printed implant-retained mandibular overdentures (IMO) are more satisfactory for edentulous seniors than those made through traditional methods.

METHODS/DESIGN

We will recruit 26 completely edentulous participants (any sex/gender) based on the following eligibility criteria: age ≥ 60 years, no tooth extraction in the past 12 months, two implants in the lower jaw, and need for new dentures in both jaws. Each participant will receive two denture pairs, either manufactured by 3D printing or traditionally, to be worn in a random order. A timeline of 3 months with each denture pair will be considered for outcome assessment (total: 6 months). Patient satisfaction with dentures will be measured by the McGill Denture Satisfaction Questionnaire. We will evaluate other patient-reported outcomes (including oral health-related quality of life) as well as clinician-assessed quality and cost. At the end of the trial, participants will choose which denture pair they wish to keep and interviewed about their experiences with the 3D-printed IMO. The quantitative and qualitative data will be incorporated through an explanatory mixed-methods strategy. A final quantitative assessment will happen after 12 months with the preferred IMO to assess the long-term performance and maintenance needs.

DISCUSSION

This mixed-methods RCT will explore patient experiences with 3D-printed IMOs, aiming to assess the potential for altering clinical practice and dental public health policies. Our results will inform policies by showing whether 3D printing offers comparable outcomes at lower costs, facilitating greater access to oral care for the elderly.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT06155630, Registered on 04 December 2023. https://classic.

CLINICALTRIALS

gov/ct2/show/NCT06155630.

A systematic review and meta-analysis of the clinical performance of implant-supported overdentures retained by CAD-CAM bars

Currently, there is no consensus on the indications and clinical performance of implant-supported overdentures (IODs) involving computer-aided design and manufacturing (CAD-CAM) bars.

OBJECTIVE

To evaluate the performance of IODs involving CAD-CAM bars.

METHODOLOGY

A comprehensive search of studies published until May 2023 was conducted in many databases, including PubMed/MEDLINE, Web of Science, Cochrane Library, and SciELO, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The population, intervention, comparison, outcome (PICO) question was: "How do IODs retained by bars fabricated by CAD-CAM technology perform in daily clinical practice?" The meta-analysis included clinical studies based on effect size and a two-tailed null test with a 95% confidence interval (CI).

RESULTS

Ten studies were included in the meta-analysis. Among them, nine reported a 100% implant survival rate for all CAD-CAM milled bars. Complications were reported in two studies with CAD/CAM-milled titanium bars, and one study reported more fractures in soldered gold bars used in maxillary rehabilitation. However, no fractures were observed in IODs retained by PEEK and zirconia bars. According to six studies, biological complications, including peri-implantitis, were minimal in the BioHPP and PEEK bar groups, while no cases were reported in the titanium or zirconia bar groups. CAD-CAM-milled zirconia bars had higher plaque and bleeding indices compared with titanium bars, as evidenced by findings from five studies. All four studies that evaluated Oral Health Impact Profile (OHIP) scores showed a positive effect of IODs retained by CAD-CAM milled titanium bars on quality of life. Patient satisfaction and acceptance by prosthodontists were significantly high, according to the results of five studies.

CONCLUSION

Overdentures retained with CAD-CAM milled titanium bars show great potential for use in daily clinical practice. Moreover, patient and practitioner satisfaction was very high when this method was used.

Effect of Ball and Bar Attachment Type on Patient Satisfaction Using Two-Implant-Retained Mandibular Overdenture: A Crossover Randomized Clinical Trial

Background

Considering the two-implant-retained overdenture as a first treatment of choice for edentulous mandible, patients using the overdentures need to be satisfied with the type of attachment used. The purpose of this study was to determine level of patient satisfaction with two-implant-retained mandibular overdentures opposing conventional maxillary complete denture using ball-socket and bar-clip attachments.

Materials and Methods

In this within-subject crossover randomized clinical trial, total 20 edentulous patients were given conventional complete dentures for 3 months to use. All completed a satisfaction questionnaire before implant placement. They were randomly assigned to receive an overdenture retained by either ball or bar attachment. After 3 months satisfaction questionnaires were repeated, and crossover was done by changing the attachments. After use of 3 months of alternate attachments, patients were asked to complete the final questionnaires and asked to choose their preferred type. The patient satisfaction scores were recorded after using 3 months of conventional complete denture, 3 months of first attachment and 3 months of second attachment. Data were analyzed using Wilcoxon signed rank test. The P values were adjusted using Bonferroni multiple testing correction, and P < .05 were considered as statistically significant.

Results

There was no significant difference in patient satisfaction between ball and bar attachments. However, patient satisfaction improved significantly between baseline and either-attachment-retained prosthesis. At the end of the comparative crossover experiment, 11 patients voted for the ball attachments and 9 for the bar attachments, thereby indicating them as their preferred attachments.

Conclusions

Among ball and bar attachment, there was no statistically significant difference in satisfaction scores. Neither ball nor bar attachment was chosen as a preference over the other.

Attachment systems for mandibular implant-supported overdentures: A systematic review and meta-analysis of randomized controlled trials

STATEMENT OF PROBLEM

Although mandibular implant-supported overdentures have been highly recommended as a treatment option, a consensus on the type of attachment systems that can be used to increase implant and prostheses survivability is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare different types of attachments for retention by investigating outcome measures such as implant and prosthesis survival rates and biological and prosthesis complications in participants with a mandibular implant-supported overdenture.

MATERIAL AND METHODS

The search was performed in the PubMed, Cochrane, Embase, and Scopus databases by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria and registered with the International Prospective Register of Systematic Reviews (CRD42021253566). An analysis of association was conducted between different attachment systems and implant and overdenture survival rates in randomized controlled clinical trials.

RESULTS

The initial search indicated 477 studies, of which 25 randomized controlled trials (RCTs) were included for analysis. A total of 2154 implants and 737 overdentures were analyzed in the meta-analysis. The main results indicated the failure rate for dental implants to be 2.0% (95% confidence interval [CI], 1.3 to 3.2) and overdentures 4.2% (95% CI, 1.6 to 10.5), respectively. With regard to different attachment systems, a similar failure rate was identified with bar-type retention (7.7% to 95% CI, 3.0 to 18.1), magnetic retention systems (7.6% to 95% CI, 2.2 to 22.7), and ball-type retention (6.8% to 95% CI, 3.0 to 14.3). No significant difference was found in biological complications for splinted and unsplinted implant overdentures (P=.902). Regarding prosthetic complications, the most favorable groups were LOCATOR attachments followed by telescopic and Conus, bar, and ball attachments. Magnet attachments had higher prosthetic complications (7.4 times) than the other attachments.

CONCLUSIONS

Implants and implant-supported mandibular overdentures showed a high survival rate irrespective of the attachment system used. Splinting implants did not significantly affect the rate of biological complications. Prosthetic complications were most common for magnet and least common for LOCATOR attachments.

Ideal set-up angle between a pair of oval dental magnetic attachments for suppression of the loss in retentive force associated with horizontal displacement

Two oval sandwich type magnetic attachments set up in various angulations and spacing, then the pattern of retentive force against horizontal displacement studied. A measuring device and methodology that matches ISO 13017 was used. A pair of magnetic attachments fixed on the same plane at a specific distance on the measuring device and set in various angulations. Retentive force readings of magnetic attachments in various setup positions against the horizontal displacement along the major or minor axis directions were taken. The pattern of decline in retentive force as horizontal displacement increased was different across the various set-ups. It was found that the decrease in retentive forces associated with horizontal displacement can be suppressed when the angle between the major axis and the direction of movement is as small as possible. Formation of a 90° angle between major axes of any pair of magnetic attachments led to nullification of the decline in retentive forces associated with displacement in any direction. Therefore, 90° is the practical, ideal set-up angle between any pair of dental magnetic attachments critical for suppression of the loss in retentive force associated with horizontal gap.

Do ball-type attachment systems for overdenture result in better patient-satisfaction? A systematic review of randomized crossover clinical trial

Objective

This review is to compare patient-satisfaction with ball-type overdenture attachment systems with others attachment systems.

Material and methods

This study was registered in PROSPERO (CRD42018097234) and adheres the PRISMA guidelines. Electronic searches on PubMed/MEDLINE, Scopus, Cochrane, and Web of Science databases for published articles were performed before October 2020. The PICO question was: “Do patients with a ball-type overdenture retention system have greater satisfaction, when compared to other attachment systems?” The evaluation of risk of bias was performed using the Cochrane risk of bias tool.

Results

After searching the databases, seven articles were selected out of a total of 2583. A total of 312 implants were placed in 139 patients, with a mean age of 65.9 years. The risk of bias in the included studies varied according to the different domains in a risk of uncertain bias or low bias risk. No difference was found between the ball attachment systems and the others systems, with respect to patient-satisfaction. The meta-analysis revealed no statistically significant difference between the ball systems and another systems (P = 0.11; MD: 10.90; 95% CI: −2.55 to 24.35).

Conclusions

Regarding patient general satisfaction, it was not possible to determine differences between the ball system and another types of attachment system for overdenture. The ball-type system was statistically superior only to the magnet system.

Patient satisfaction and masticatory performance of zirconia bar compared to cobalt chromium bar retaining mandibular implant overdenture: A crossover study

OBJECTIVES

The aim of this crossover clinical study was the evaluation and comparison of patient satisfaction and masticatory performance for patients rehabilitated with mandibular two implant overdentures retained with two different bar attachments: zirconia bar and cobalt chromium bar.

MATERIAL AND METHODS

Twenty completely edentulous patients were divided into two equal groups: Group I (ZrO2), each patient received mandibular implant overdenture retained with CAD/CAM zirconia bar on two implants in the canine region, and Group II (Co-Cr), each patient received mandibular overdenture retained with conventional casted cobalt chromium metal bar. Patient satisfaction was measured with a survey questionnaire (PSQ-18), and masticatory performance was also evaluated with the two-colour mixing ability test after 3 months of overdenture insertion; then, each patient received a bar attachment from the other type and evaluations were repeated.

RESULTS

Significant differences were observed regarding psychological acceptance (appearance), time, hygiene, undergo procedures, recommend procedures and the overall experience. In contrast, insignificant difference was observed regarding speech, chewing capacity, restorative procedures, complications and information prior to treatment. No significant difference was reported when comparing chewing performance between the two types of bar attachment.

CONCLUSION

Within this clinical study limitations, patient satisfaction with zirconia bar was higher than Co-Cr bar in terms of appearance, time, hygiene, undergo procedures, recommend procedures and the overall experience. Zirconia can become a suitable alternative to cobalt chromium alloys as a bar attachment. Combining the advantages of implant supported overdenture, CAD/CAM zirconia bar as an attachment, a satisfactory non-metal prosthesis could be provided.

Effects of overdenture attachment systems with different working principles on stress transmission: A three-dimensional finite element study

PURPOSE

The aim of the present study was to compare the stress distributions on the dental implants, abutments, and bone caused by different overdenture attachment types under functional chewing forces.

MATERIALS AND METHODS

The 3D finite element models of the mandible, dental implants, attachment types, and prostheses were prepared. In accordance with a conventional dental implant supported overdenture design, the dental implants were positioned at the bone level in the canine teeth region bilaterally. A total of eight models using eight different attachment systems were used in this study. All the models were loaded to simulate chewing forces generated during the centric relationship (450 N), lateral movement (400 N), protrusive movement (400 N), and also in the presence of a food mass unilaterally (200 N). Stress outputs were obtained as the maximum principal stress and the equivalent von-Mises stress.

RESULTS

In all attachment types, higher stress values were observed in the abutments, dental implants, and bone in the magnet attachments in different loading conditions. The highest stress values were observed among the magnet systems in the components of the Titanmagnetics model in all loading conditions (stresses were 15.4, 17.7, and 33.1 MPa on abutment, dental implant, and bone, respectively). The lowest stress value was observed in the models of Zest and O-Ring attachments.

CONCLUSION

The results of the present study implied that attachment types permitting rotation and tolerating various angles created lower stresses on the bone, dental implants, and abutments.

Attachment-retained removable prostheses: Patient satisfaction and quality of life assessment

STATEMENT OF PROBLEM

Studies on the impact of incorporating attachments in removable prostheses on patient-based outcomes are scarce.

PURPOSE

The purpose of this clinical study was to investigate oral health-related quality of life (OHRQoL) and patient satisfaction in partially edentulous participants before and after rehabilitation with mandibular attachment-retained removable prostheses as compared with conventional removable prostheses.

MATERIAL AND METHODS

This crossover study included 74 participants (aged 36 to 57). Initially, 56 received conventional clasp-retained removable dental prostheses (RDPs), and 18 received conventional overdentures (ODs) based on their mandibular partially edentulous state. Two months later, of the 56 RDP participants, 24 had received extracoronal attachment-retained RDPs, 17 received telescope-retained RDPs, and 15 received bar-attachment retained RDPs. The 18 OD participants received ball attachment-retained ODs. Assessments included Oral Health Impact Profile-short version-14 for OHRQoL and a visual analog scale (VAS) for patient satisfaction. Assessments were done before treatment and 2 months after wearing each prosthesis with a 1-month washout period. Statistical analysis included the Friedman then the Wilcoxon signed rank test for Oral Health Impact Profile-short version-14 scores and repeated measures ANOVA then the Bonferroni or paired t test for VAS scores (α=.05).

RESULTS

There were no dropouts. Rehabilitation, irrespective of prosthesis type, significantly improved OHRQoL in all domains and significantly increased overall patient satisfaction (P<.05). When compared with the conventional prostheses, attachment-retained prostheses significantly improved functional limitation, psychological discomfort, and physical limitation domains in all groups (P<.05), as well as the physical pain domain in the OD group (P=.041). General satisfaction, stability, comfort, ability to speak, and ability to masticate significantly increased (P<.05) with attachment-retained prostheses. Conventional prostheses were significantly easier to clean (P<.05) in all groups, except for the telescope-attachment group.

CONCLUSIONS

Both conventional and attachment-retained prostheses significantly increased patient satisfaction and improved OHRQoL in all domains as compared with before treatment. However, incorporation of attachments further improved functional limitation, psychological discomfort, and physical limitation domains in all groups, as well as the physical pain domain in the OD group. Participants were more satisfied with their attachment-retained prostheses in most aspects.

Implant-Supported Prosthesis for Edentulous Patient Rehabilitation. From Temporary Prosthesis to Definitive with a New Protocol: A Single Case Report

This case study concerns a patient who had lost all of his teeth, needing a rehabilitation with total prosthesis, who went to the dentist looking for help to overcome psycho-physical trauma and to overcome functional and social problems related to being a prosthesis wearer. Tooth loss occurs most in old age, even if it is not a direct consequence of aging. The rehabilitation of oral functions allows the patient to speak, chew, smile and feel confident in his own aesthetics and therefore improve, even a lot, his well-being in social relations. It is very important in oral rehabilitations to evaluate their type and therapeutic timing. This study stems from the idealization of a new protocol to simplify the supported oral rehabilitations. In this manuscript, a patient was considered and shown according to a complete photographical documentation all the phases. Rehabilitation included the use of Osstem (Osstem, Seoul, Korea) and equator type abutments (Rhein83, Bologna, Italy). This manuscript claims to represent the first of a whole series of cases demonstrating the utility of this protocol.

Effect of mucosa thicknesses on stress distribution of implant-supported overdentures under unilateral loading: Photoelastic analysis

INTRODUCTION

The aim of this study was to evaluate the effect of different heights of attachment and mucosa thicknesses on the stress distribution of two implant-retained mandibular overdenture designs under loading using the photoelastic stress analysis method.

MATERIALS AND METHODS

Six photoelastic models of an edentulous mandibula were fabricated with two solitary implants that were placed in the canine regions. The attachment systems studied were ball and locator stud attachments. Both the ball and locator groups included three models that had different residual ridge heights so as to provide different mucosa thicknesses (1 mm-1 mm, 1 mm-2 mm, 1 mm-4 mm). A static vertical force of 135 N was applied unilaterally (each on the right then the left side) to the central fossa of the first molars. Models were positioned in the field of a circular polariscope to observe the distribution of isochromatic fringes around the implants and the interimplant areas under loading. The photoelastic stress fringes were monitored and recorded photographically.

RESULTS

The ball attachment groups showed higher stress values than did the locator groups under loading. Both attachment systems produced the lowest stress values in stimulated 1 mm-1 mm mucosa thickness models. The models with 1 mm-2 mm mucosa thicknesses showed higher stress values than did other models for both attachment systems. The highest stress value observed around both attachment systems was the moderate level in all test models.

CONCLUSION

In different height mucosa thicknesses, locator attachment models distributed the load to the other side of the implant and its surrounding tissue, whereas the ball attachment did not. Regardless of mucosal thickness and attachment type, the implant on the loading side was subjected to the highest stress concentration.

Comparison of Three Different Types of Two-Implant-Supported Magnetic Attachments on the Stress Distribution in Edentulous Mandible

Two-implant-retained mandibular overdentures with magnetic attachments can provide an effective treatment modality for edentulous patients. In this study, a three-dimensional finite element analysis was used to compare the biomechanical characteristics of three different types of magnetic attachments in two-implant-retained mandibular overdentures. Flat-type, dome-type, and cushion-type of the magnetic attachments were designed to retain the overdenture. Four types of load were applied to the overdenture in each model: 100 N vertical and oblique loads on the right first molar and a 100 N vertical load on the right canine and the lower incisors. The biomechanical behaviors of peri-implant bone, abutment, and mucosa were recorded. In vertical incisors, vertical right canine, and oblique molar loading condition, the flat-type group exhibited the highest levels of maximum equivalent strain/stress in the peri-implant bone. The total deformation of mucosa and the maximum equivalent strain/stress in the oblique molar loading condition are about two times as the vertical molar loading condition. These results suggested that both cushion-type and dome-type of the magnetic attachments are better choices in two-implant-retained mandibular overdentures, and oblique loading is more harmful than vertical loading.

Comparison of immediate and conventional loading protocols with respect to marginal bone loss around implants supporting mandibular overdentures: A systematic review and meta-analysis

Purpose

To compare marginal bone level changes (MBLCs) of immediately- and conventionally-loaded implants supporting a mandibular implant overdenture (IOD).

Materials and methods

Both electronic (MEDLINE, PubMed, and The Cochrane Library) and manual searches were conducted for all relevant studies published from 1 January 2000 to 1 November, 2017. Randomized controlled trials (RCTs) and prospective studies with a minimum follow-up of 12 months were selected. Studies which utilized implants narrower than 3 mm were excluded from analysis.

Results

Four studies met the criteria, with two evaluating horizontal bone loss. There were 70 patients in the test group (immediate loading) and 60 in the control group (conventional loading). Follow-up lasted 6–36 months, with MBLCs being interpreted from standardized periapical x-rays, panoramics or cone beam computed tomography. Each patient was given 2–3 implants.

After 6 and 12 months, the differences in MBLCs were 0.04 mm (95% CI: −0.21, 0.29) and 0. 00 mm (95% CI: −0.35, 0.36) respectively. Subgroup analysis of RCTs with 2 implants revealed group differences in MBLCs as 0.13 mm (95% CI: −0.22, 0.48) and that in horizontal bone loss as 0.04 mm (95% CI: −0.02, 0.10). No statistically significant differences were identified (p > 0.05).

Conclusion

The MBLCs of immediately-loaded implants for mandibular IODs seems comparable to those of conventional loading.

Single-implant overdentures retained by the Novaloc attachment system: study protocol for a mixed-methods randomized cross-over trial

BACKGROUND

Overdentures retained by a single implant in the midline have arisen as a minimal implant treatment for edentulous mandibles. The success of this treatment depends on the performance of a single stud attachment that is susceptible to wear-related retention loss. Recently developed biomaterials used in attachments may result in better performance of the overdentures, offering minimal retention loss and greater patient satisfaction. These biomaterials include resistant polymeric matrixes and amorphous diamond-like carbon applied on metallic components. The objective of this explanatory mixed-methods study is to compare Novaloc, a novel attachment system with such characteristics, to a traditional alternative for single implants in the mandible of edentate elderly patients.

METHODS/DESIGN

We will carry out a randomized cross-over clinical trial comparing Novaloc attachments to Locators for single-implant mandibular overdentures in edentate elderly individuals. Participants will be followed for three months with each attachment type; patient-based, clinical, and economic outcomes will be gathered. A sample of 26 participants is estimated to be required to detect clinically relevant differences in terms of the primary outcome (patient ratings of general satisfaction). Participants will choose which attachment they wish to keep, then be interviewed about their experiences and preferences with a single implant prosthesis and with the two attachments. Data from the quantitative and qualitative assessments will be integrated through a mixed-methods explanatory strategy. A last quantitative assessment will take place after 12 months with the preferred attachment; this latter assessment will enable measurement of the attachments' long-term wear and maintenance requirements.

DISCUSSION

Our results will lead to evidence-based recommendations regarding these systems, guiding providers and patients when making decisions on which attachment systems and implant numbers will be most appropriate for individual cases. The recommendation of a specific attachment for elderly edentulous patients may combine positive outcomes from patient perspectives with low cost, good maintenance, and minimal invasiveness.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03126942 . Registered on 13 April 2017.

Implant retention systems for implant-retained overdentures

Implant retained overdentures are being increasingly utilised in both general and specialist practice to rehabilitate patients with missing teeth, particularly those that are edentate. This article aims to inform the reader of a variety of retention systems that are available to retain an implant overdenture and to understand how these systems work, their advantages and disadvantages and to outline some of the clinical and treatment planning considerations involved in selecting the most appropriate retention system for patients.

Mandibular Implant-supported Overdentures: Prosthetic Overview

Implant-supported overdentures are becoming the treatment of choice for the completely edentulous mandible. They significantly improve the quality of life in edentulous patients. For this review article, the literature was searched to identify pertinent studies. No meta-analysis was conducted because of high heterogeneity within the literature. Accordingly, in this review article, the author provides an update on implant-supported mandible overdentures with regard to the number of implants, type of loading, stress-strain distribution, mode of implant-to-denture attachment, occlusal considerations and complications.

The influence of immediately loaded implant treatment in the atrophic edentulous maxilla on oral health related quality of life of edentulous patients: 3-year results of a prospective study

Background

To evaluate oral health related quality of life (OHQoL) in edentulous patients treated with immediately loaded implants in the maxilla.

Methods

Fifty-one edentulous patients in two centers received six maxillary implants each were loaded within 24 h with provisional restoration. Definitive restoration was delivered 20–24 weeks later. OHQoL was evaluated preoperatively with the Oral Health Impact Profile 49 questionnaire (OHIP-49) and on five subsequent occasions. OHIP-49 includes seven domains representing functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and handicap. A reduction in OHIP scores indicated an improved OHQoL.

Results

Forty-five patients reached the three-year follow up. OHQoL improved after treatment. A plateau of OHQoL improvement was observed at 12 months after surgery. The seven domains improved at different pace, 12 weeks to 12 months after treatment. OHIP showed continuously low scores with no significant changes at consecutive visits 12 months to three years after treatment. Dental status with removable prosthesis in the mandible had a negative impact on OHQoL prior to and during treatment, but did not affect OHQoL after permanent restoration was placed. Patients age or gender did not affect OHQoL.

Conclusions

Patients with edentulous maxilla who received prosthetic rehabilitation on immediately loaded implants experienced the highest improved OHQoL 12 months after implant installation. Quality of life related to oral health continued to be high after three years. Edentulous patients with atrophy of the maxilla experience an improved OHQoL after implant treatment with immediate loading protocol.

Trial registration

ClinicalTrials.gov Identifier NCT00711022.

Effect of implant- and occlusal load location on stress distribution in Locator attachments of mandibular overdenture. A finite element study

PURPOSE

The aim of this study is to evaluate and compare the stress distribution in Locator attachments in mandibular two-implant overdentures according to implant locations and different loading conditions.

MATERIALS AND METHODS

Four three-dimensional finite element models were created, simulating two osseointegrated implants in the mandible to support two Locator attachments and an overdenture. The models simulated an overdenture with implants located in the position of the level of lateral incisors, canines, second premolars, and crossed implant. A 150 N vertical unilateral and bilateral load was applied at different locations and 40 N was also applied when combined with anterior load at the midline. Data for von Mises stresses in the abutment (matrix) of the attachment and the plastic insert (patrix) of the attachment were produced numerically, color-coded, and compared between the models for attachments and loading conditions.

RESULTS

Regardless of the load, the greatest stress values were recorded in the overdenture attachments with implants at lateral incisor locations. In all models and load conditions, the attachment abutment (matrix) withstood a much greater stress than the insert plastic (patrix). Regardless of the model, when a unilateral load was applied, the load side Locator attachments recorded a much higher stress compared to the contralateral side. However, with load bilateral posterior alone or combined at midline load, the stress distribution was more symmetrical. The stress is distributed primarily in the occlusal and lateral surface of the insert plastic patrix and threadless area of the abutment (matrix).

CONCLUSION

The overdenture model with lateral incisor level implants is the worst design in terms of biomechanical environment for the attachment components. The bilateral load in general favors a more uniform stress distribution in both attachments compared to a much greater stress registered with unilateral load in the load side attachments. Regardless of the implant positions and the occlusal load application site, the stress transferred to the insert plastic is much lower than that registered in the abutment.

Stress distribution patterns of implant supported overdentures-analog versus finite element analysis: A comparative in-vitro study

Aims and Objectives:

The aim of this study was to asses & compare the load transfer characteristics of Ball/O-ring and Bar/Clip attachment systems in implant supported overdentures using analog and finite element analysis models.

Methodology:

For the analog part of the study, castable bar was used for the bar and clip attachment and a metallic housing with a rubber O-ring component was used for the ball/O-ring attachment. The stress on the implant surface was measured using the strain-gauge technique. For the finite element analysis, the model were fabricated and load applications were done in a similar manner as in analog study.

Results:

The difference between both the attachment systems was found to be statistically significant (P<0.001).

Conclusion:

Ball/O-ring attachment system transmitted lesser amount of stresses to the implants on the non-loading side, as compared to the Bar-Clip attachment system. When overall stress distribution is compared, the Bar-Clip attachment seems to perform better than the Ball/O-ring attachment, because the force was distributed better.

Implant-retained prostheses: ball vs. conus attachments - A randomized controlled clinical trial

OBJECTIVE

To evaluate implant survival, peri-implant tissue conditions, prosthodontic maintenance requirements and patient satisfaction of two differently retained implant-supported mandibular overdentures (IOD) after the 3 years of observation.

MATERIALS AND METHODS

Twenty-five patients with edentulous mandibles received two implants each. Twelve patients were randomly selected to receive ball attachments, whereas 13 patients received prefabricated coni. Implant survival, peri-implant parameters (modified Plaque Index, Bleeding on Probing, modified Gingival Index, probing depth and marginal bone loss) and patient satisfaction were assessed. Additionally, prosthodontic maintenance was monitored. Clinical and radiographic follow-ups were performed 1, 2 and 3 years after prosthetic delivery. The Kaplan-Meier method was used to calculate complication rates.

RESULTS

After a mean observation period of 29.6 months, an implant survival rate of 100% could be observed. There were no significant differences in the peri-implant parameters. During the observation period, six patients with conus attachment refused to further participate in follow-ups due to dissatisfaction with their treatment and had to be regarded as dropouts. Based on the Kaplan-Meier method, inacceptable retention was calculated for 80% and 75% of the patients in the ball and the conus groups, respectively. Patient satisfaction was 64% for the ball- and 100% for the conus-retained IODs, the latter only respecting five of initially 13 patients.

CONCLUSION

The evaluated treatment method revealed high implant survival rates, but the prosthetic reconstruction required intensive maintenance. Therefore, a trend toward the reduced patient satisfaction was observed, and the promoted economy of the evaluated attachment systems should be questioned. For the conical attachment, the recommendation of the manufacturer is to use four interforaminal implants to support a removable prostheses.

Locators versus magnetic attachment effect on peri-implant tissue health of immediate loaded two implants retaining a mandibular overdenture: a 1-year randomised trial

This study aimed to evaluate peri-implant tissue health of immediate loaded two implants retaining a mandibular overdenture with either magnetic or locator attachment. Thirty two completely edentulous patients (20 males/12 females) were randomly assigned into two groups. Each patient received two implants in the canine area of the mandible using flapless surgical technique. Mandibular overdentures were immediately connected to the implants with either magnetic (group I, GI) or locator (group II, GII) attachments. Peri-implant tissue health was evaluated clinically in terms of plaque scores (PI), bleeding scores (BI), probing depth (PD), implant stability (ISQ) and interleukin-1-β (IL-1b) concentrations in peri-implant sulcular fluid. PI, BI and PD were measured at mesial, distal, buccal and lingual surfaces of each implant. Radiographic evaluation was performed in terms of vertical (VBL) and horizontal (HBLO) alveolar bone loss. Evaluations were performed 2 weeks (T0), 6 months (T1) and 12 months (T2) after overdenture insertion. Plague scores, PD, IL-1b, VBL and HBLO increased significantly with time. ISQ decreased significantly with time. BI showed no significant differences between observation times. GI recorded significant higher PI, ISQ and IL-1b at T2 compared to GII. GII recorded significant higher VBL than GI at T2 only. For HBLO, no significant differences between groups were noted. VBL and HBLO showed a significant positive correlation with PD. Locator attachments for immediate loaded implants retaining mandibular overdentures are associated with decreased plaque accumulation, decreased implant stability, decreased interleukin-1β concentration in peri-implant crevicular fluid and increased per-implant vertical bone loss compared to magnetic attachments after 1 year.

Mini vs. Standard Implants for Mandibular Overdentures

A mandibular implant-retained overdenture is considered a first-choice treatment for edentulism. However, some aspects limit the use of standard implants—for example, the width of edentulous ridges, chronic diseases, fear, or costs. This randomized trial compared mandibular overdentures retained by 2 or 4 mini-implants with standard implants, considering oral health–related quality of life (OHRQoL), patient satisfaction, and complications such as lost implant. In sum, 120 edentulous men and women (mean age, 59.5 ± 8.5 y) randomly received 4 mini-implants, 2 mini-implants, or 2 standard implants. Participants provided data regarding OHRQoL and satisfaction until 12 mo. Clinical parameters, including implant survival rate, were also recorded. Both 2 and 4 mini-implants led to better OHRQoL, compared with 2 standard implants. Treatment with 4 mini-implants was more satisfying than 2 standard implants, with 2 mini-implants presenting intermediate results. Implant survival rate was 89%, 82%, and 99% for 4 mini-implants, 2 mini-implants, or 2 standard implants, respectively. Overdentures retained by 4 or 2 mini-implants can achieve OHRQoL and satisfaction at least comparable with that of 2 standard implants. However, the survival rate of mini implants is not as high as that of standard implants ( ClinicalTrials.gov NCT01411683).

Strain characteristics of Marburg double crown-retained implant overdentures compared with bar and ball-retained implant overdentures, with and without a rigid major connector

STATEMENT OF PROBLEM

It is hard to identify the most favorable retainer type and the denture design when considering strain levels around implants and in edentulous ridges for implant overdentures (IOVD).

PURPOSE

The purpose of this study was to evaluate the strain transmitted to the implants and edentulous ridges by Marburg double crown (MDC)-retained IOVD as opposed to bar and ball-retained IOVD and the efficiency of a rigid major connector in the maxilla.

MATERIAL AND METHODS

An in vitro maxillary model was prepared with 4 implants, with strain gauges placed distally to each implant and also in the anterior and posterior edentulous ridges. Five overdentures were fabricated for each MDC and each ball and bar attachment retainers. Vertical loads of 280 N were applied bilaterally on the first molar region. Then the palatal bars of each IOVD were disconnected, and loading procedures were repeated for the prostheses.

RESULTS

No significant difference was observed among the MDC and the bar and ball-retained IOVD, with and without a rigid bar according to the data taken from both the implants and edentulous ridges. However, when the strain values attained from each strain gauge separately were considered, a slight difference was observed around the implants of ball-retained overdentures and in the edentulous ridges of MDC-retained overdentures.

CONCLUSIONS

Within the limitations of this in vitro study, MDC-retained maxillary overdentures with 4 parallel and symmetrically placed implants can be used safely without a rigid major connector as with bar and ball-retained IOVD with regard to the strains generated in the edentulous ridge and around implants.

Effect of Implant Height Differences on Different Attachment Types and Peri-Implant Bone in Mandibular Two-Implant Overdentures: 3D Finite Element Study

Implant-supported overdentures with self-aligning attachment systems are preferred to improve the stability and retention of complete dentures. The positioning of the implant attachments is a very important aspect of two-implant overdentures in obtaining better stress distribution. Therefore, the objective of this study was to compare two different attachment systems in a two-implant overdenture by evaluating the stress distributions in peri-implant bone and stresses on the attachments with positioning at different height levels using the 3D FEA method. Six models with ball attachments and 6 models with locator attachments-totaling 12 models (including 2 controls)-with the left implant positioned unilaterally at different height levels were subjected to 3 loading conditions (anterior, right posterior, and left posterior). Data for Von Misses stresses were produced numerically, color coded, and compared among the models for attachments and peri-implant cortical bone. The configurations in which implants presented 3 mm height differences in the bone level showed the most successful results in the peri-implant bone. When stresses on the attachments were compared, greater stress values were obtained from the ball attachments. As a conclusion, the configurations with a considerable (3 mm) height difference between quadrants of the mandible in the anterior segment showed the most successful results in the peri-implant bone. On the contrary, peak stress values around the implant observed from the models with less (1 mm) bone height difference may require leveling of the bone during surgery. However, these findings should be corroborated with clinical studies.