Prosthetic maintenance of different mandibular implant overdentures: A systematic review

Effect of implant angulation and patrice on the retention of overdenture attachment systems: An in vitro study

PURPOSE

To test the retention of two different overdenture attachment matrices and straight abutments when implants are placed at 0-, 15-, and 30-degree diverging angulations as well as the retention of 15-degree-angled abutments to correct the overall angulation to 0-degrees.

MATERIALS AND METHODS

Matching aluminum blocks were machined to incorporate two dental implants at 0-degree, 15-degree, and 30-degree relative angulations and overdenture attachments to simulate a two-implant overdenture. At 0-degree, 15-degree, and 30-degree implant angulation, straight abutments were studied. At 30-degree implant angulation, an additional group was compared utilizing 15-degree angulated abutments that corrected the overall implant angulation to 0-degrees. A custom-designed testing apparatus that allowed automated insertion and removal of the simulated overdenture was designed, with three independent testing stations, each consisting of one simulated arch and one simulated overdenture base. The baseline and residual retention forces after 30,000 dislodging cycles of the simulated overdenture were measured. One-way ANOVA was used to compare retention differences among different color patrices within the 0-, 15-, and 30-degree implant angulation groups followed by Tukey's multiple comparison test. Two sample t-tests were used to compare 0-degree versus 15-degree implant groups with straight abutments and 30-degree implant groups with straight abutments versus 30-degree implant groups with angulated abutments.

RESULTS

Regardless of implant angulation or abutment correction, the change in retention exhibited by the Novaloc system after testing was not statistically significant for all patrice types (p > 0.05); however, the change in retention exhibited by the Locator system was statistically significant for the tested group (p = 0.0272). In both the Novaloc and Locator systems, the baseline and final retention values provided by the different patrices were significantly different except for the white and green Novaloc patrices in the 15-degree divergent implant group which did not meet the specified level of significance (p = 0.0776).

CONCLUSION

Within the limitations of this study, implant angulations upto 15 degrees do not affect differential change in retention of Novaloc patrices. There is no difference between Novaloc white inserts (light retention value) and green inserts (strong retention values) when implants diverge upto 15 degrees. When Novaloc straight abutments were placed on implants diverging by 30 degrees, blue extra-strong retention inserts outperformed yellow medium retention inserts by maintaining a higher retention value after 30,000 cycles. When utilizing Novaloc 15-degree angulated abutments that correct the overall implant angulation to zero degrees, the red light retentive patrice provides steady retention. Finally, the Locator-green patrice system provides greater retention than the comparable Novaloc-blue patrice combination; however, it also loses more retention after 30,000 cycles.

Patient-reported outcome measures and clinical performance of implant-retained mandibular overdentures with stud and ball attachments: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Evidence regarding the retention system for a mandibular overdenture is important for treatment planning. However, the clinical performance of stud and ball attachments for mandibular overdenture retainers is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare the clinical performance and self-reported patient outcomes of ball and stud attachments as mandibular overdenture retainers.

MATERIAL AND METHODS

Randomized (RCTs) and nonrandomized (N-RCTs) controlled clinical trials were selected based on the eligibility criteria. The risk of bias was assessed by using the Cochrane Collaboration Tools, and the certainty of the evidence (COE) by using the grades of recommendation, assessment, development, and evaluation (GRADE) workshop approach. Meta-analyses according to the follow-up period were performed for implant survival, prosthetic maintenance and complications, bleeding on probing (BoP), marginal bone loss (MBL), satisfaction, and oral health-related quality of life (OHRQoL).

RESULTS

Thirteen RCTs and 4 N-RCTs were included. Twelve studies presented a high risk of bias. The stud demonstrated a lower risk ratio (RR) (P<.001) for maintenance and complications concerning the need for matrix activation (RR 7.12 [2.65, 19.15]) (very low COE) and new overdentures (RR 2.47 [1.02, 5.96]) (moderate COE), ranging from 1 to 5 years of follow-up. Mean difference (MD) for MBL after 1 (MD 0.40 [0.28, 0.52]; P<.001) and 5 years (MD 0.18 [0.16, 0.20]; P<.001) was higher for ball attachments than that for stud (very low COE) attachments. Stud attachments also improved satisfaction (P<.001) when compared with ball attachments (very low COE). Implant survival rate (high COE), BoP (very low COE), and OHRQoL (low COE) were similar for the attachments.

CONCLUSIONS

Stud and ball attachments are clinically appropriate options as mandibular overdenture retainers and are capable of restoring OHRQoL. Nevertheless, the stud showed greater improvement in satisfaction and less prosthetic aftercare and MBL.

Effect of thermocycling on the retentive force of the retentive inserts in three denture attachments and their water absorption ability

This study aimed to evaluate the thermocycling effect on the retentive force of 3 different retentive inserts in 3 denture attachments (Blue, Pink, Clear retentive inserts in LOCATOR; Blue, Pink, Clear retentive inserts in LOCATOR R-Tx; and White, Yellow, Green retentive inserts in Novaloc) (n=10). Maximum retentive force of each retentive insert was evaluated at baseline, 7-day water storage, and after 5,000-, and 10,000- cycle thermocycling. The water absorption percentage of the retentive inserts was also determined. Comparing between baseline and 7-day water storage, the retentive forces of the LOCATOR and LOCATOR R-Tx groups were significantly reduced (p<0.05), while the retentive force of the Novaloc group was significantly increased (p<0.05). Comparing between 7-day water storage and 10,000-cycle thermocycling, the retentive force of most retentive inserts remained unchanged (p>0.05). The water absorption percentage of the LOCATOR and LOCATOR R-Tx groups was significantly greater than that of the Novaloc group (p<0.05).

Articulation distortion in Mandarin-speaking individuals with complete arch maxillary implant-supported fixed dental prostheses

STATEMENT OF PROBLEM

Implant-supported fixed dental prostheses (IFPs) have been increasingly used to restore edentulous jaws, yet few studies have utilized acoustic analysis for objective evaluation of postrestoration speech outcomes.

PURPOSE

The purpose of this clinical study was to assess speech articulation in edentulous individuals before and after the provision of IFPs by combining the results of subjective evaluations and objective acoustic analysis parameters.

MATERIAL AND METHODS

The study included thirty-four individuals who had an edentulous maxilla and had been provided with an IFP for over 6 months, along with 6 dentate controls. Acoustic analysis was conducted, and mean opinion scores (MOS) were rated from recordings. The participants were interviewed about perceived speech changes. Changes in the parameters were evaluated using the paired t test or Wilcoxon signed-rank test (α=.05). A comparison between dentate controls and edentulous individuals (with or without prostheses) was made using an independent t test or Mann-Whitney U test (α=.025).

RESULTS

Following restoration, the center of gravity (CoG) changes occurred in 11 of 12 consonants in edentulous individuals (P<.05). Prosthesis use allowed the CoG of all affricates and fricatives to appear larger and closer to control values. Before restoration, the CoG of 9 of 12 consonants in edentulous individuals differed from controls (P<.01); after restoration, this reduced to 3 out of 12 (P<.01). MOS improved in 10 of 12 consonants (P<.01), nearing a score of 4. Despite restoration, the CoG of alveolo-palatals [tɕh], [tɕ], and [ɕ] remained different from controls (P<.01). Most participants were satisfied with the improvement, with few reporting discomfort with alveolars [s] and [tsh].

CONCLUSIONS

IFPs can enhance speech in edentulous individuals, yet articulation distortions of alveolar and alveolo-palatal consonants persist. The improper palatal shape of IFPs or an abrupt joint between the IFP and atrophic natural bone may contribute to these distortions.

Retentive force variations in three polyamide and a polyetheretherketone denture attachments for implant-supported overdentures: An in vitro study

STATEMENT OF PROBLEM

The loss in the retentive capability of implant-supported overdenture attachments has been related to the wear of the retentive inserts. Wear of the abutment coating material when following the replacement period for the retentive inserts requires investigation.

PURPOSE

The purpose of this in vitro study was to compare the changes in retentive force of 3 polyamide and a polyetheretherketone denture attachments under repeated insertion and removal cycles in wet conditions while following their manufacturers' replacement time recommendations.

MATERIAL AND METHODS

Four different denture attachments (LOCKiT, OT-Equator, Ball attachment, and Novaloc) with their retentive inserts were tested. Four implants were embedded into individual acrylic resin blocks, and 10 abutments for each attachment were used. Forty metal housings with their retentive inserts were attached to polyamide screws with autopolymerizing acrylic resin. A customized universal testing machine was used to simulate insertion and removal cycles. The specimens were mounted on a second universal testing machine at 0, 540, 2700, and 5400 cycles, and the maximum retentive force was recorded. The retentive inserts for LOCKiT (light retention), OT-Equator (soft retention), and Ball attachment (soft retention) were replaced every 540 cycles, while the Novaloc (medium retention) attachments were never replaced. All the abutments were weighed with a precision scale at 0, 2700, and 5400 cycles. The surface of every abutment was examined under a stereomicroscope at ×10 magnification. Data were analyzed with descriptive statistics. Two-way repeated measures ANOVA was used to compare the mean retentive force and mean abutment mass of all groups and time evaluation points. Bonferroni corrections were made to adjust for multiple tests (α=.05).

RESULTS

The mean retention loss for LOCKiT was 12.6% after 6 months and 45.0% after 5 years of simulated use. The mean retention loss for OT-Equator was 16.0% after 6 months and 50.1% after 5 years of simulated use. The mean retention loss for Ball attachment was 15.3% after 6 months and 39.1% after 5 years of simulated use. The mean retention loss for Novaloc was 31.0% after 6 months and 59.1% after 5 years of simulated use. The mean abutment mass difference was statistically significant (P<.05) for LOCKiT and Ball attachment but not statistically significant (P>.05) for OT-Equator and Novaloc at baseline, 2.5 years, and 5 years.

CONCLUSIONS

All tested attachments recorded retention loss under the experimental conditions, even when their manufacturers' recommendations for replacement time for the retentive inserts were followed. Patients should be aware that implant abutments should be replaced after a recommended period since their surfaces also change over time.

Prosthodontic outcomes of mandibular overdenture treatment with one or two implants: 4-year results of a randomized clinical trial

OBJECTIVE

To assess the incidence of prosthodontic maintenance events and complications during 4 years of follow-up after mandibular overdenture treatment with one or two implants.

METHODS

Participants received one or two implants inserted in the midline (1-IOD group) or the lateral incisor-canine area bilaterally (2-IOD group). Implants were loaded with an early loading protocol after 3 weeks. Programmed recall visits were scheduled at the 6-, 12-, 36-, and 48-month follow-ups and nonprogrammed visits in case of prosthodontic complaints. The type of maintenance was registered, and the final treatment outcome was classified as successful, surviving, unknown, dead, repair, or retreatment.

RESULTS

Forty-seven participants, mean age 65.4 ± 8.6, 74.5% female, were included (1-IOD = 23; 2-IOD = 24) and 44 completed the 4-year follow-up. A total of 159 prosthodontic maintenance events occurred and 89 in unscheduled visits. The most common event was the need for minor modifications of the denture base due to sore spots in the oral mucosa (n = 56 in 31 patients), matrix activation (n = 54 in 34 patients), and overdenture fracture (n = 25 in 18 patients). A "successful" or "surviving" outcome could be attributed to 57.5% of cases, whereas 38.3% needed repair. No significant differences in the incidence of prosthodontic events or treatment outcomes were found between the two groups.

CONCLUSIONS

Findings show that 1-IODs perform similar to 2-IODs when considering the incidence of fractures and the need for prosthodontic maintenance, including adjustments of the overdenture and the attachment system.

The Biomechanical Impact of Loss of an Implant in the Treatment with Mandibular Overdentures on Four Nonsplinted Mini Dental Implants: A Finite Element Analysis

The aim of this study was to evaluate the biomechanical impact, in terms of stress and displacement, at the level of a mandibular overdenture, on four mini dental implants (MDIs) after the loss of an implant. A three-dimensional virtual model was obtained by scanning the overdenture, and a biomechanical analysis was carried out, using the finite element method (FEM). The displacements of the overdenture and the equivalent von Mises stresses were evaluated using logarithmic scales. In the case of a mandibular overdenture on four MDIs inserted in the interforaminal area, the frontal loading generated the lowest values for the von Mises stresses, and the bilateral loading generated the least displacement when two implants were inserted in the canine area and two in the molar area. The highest von Mises stress was observed during frontal loading in the situation of the mandibular overdenture on four MDIs, two of which were inserted in the canine area and two in the molar area, following the loss of an implant in the canine area. The largest displacement was noted in the mandibular overdenture on four interforaminal MDIs during unilateral loading, following the loss of a distally inserted implant. The FEM analysis showed aspects that correlated with clinical observations, with predictive value. The concentration of von Mises stresses, and the occurrence of some displacements of the prosthodontic restoration, can explain the emergence of some complications in the overdenture's biodynamics, and the increased risk of fracture. Complications can be prevented by choosing a certain number of implants and a topographical distribution correlated with biomechanical aspects, and by proposing a correct occlusal scheme with optimal functional loading.

Peri-implant stress distribution assessment of various attachment systems for implant supported overdenture prosthesis by finite element analysis - A systematic review

Background

Various attachments like ball, bar-clip, magnetic attachments are used in implant supported overdentures. Finite Element Analysis (FEA) a newly innovated technology has been used in dental implantology to evaluate stress distribution patterns. There is little evidence available regarding the stress distribution in peri-implant region for implant supported overdentures. The purpose of the review was to generate scientific evidence on peri-implant stress distribution in FEA model with different types of attachments employed in implant supported overdentures.

Materials and methods

Systematic review was conducted as per the Preferred Reporting Items for Systematic Reviews Guidelines and Meta-Analyses statement (PRISMA). A comprehensive search was undertaken by two reviewers from January 2020 to June 2020 with no year limits to published articles. Only in-vitro FEA studies were included. Following electronic databases were searched for published studies- PubMed, Web of Science. Characteristics of the studies tabulated and analysis of articles was done to compare different attachment systems.

Results

Locator attachments showed better stress distribution than ball attachment system in all the studies but one. Two studies showed results in favour of ball attachment compared to bar-clip attachment system when stress was evaluated distal to the implants. No significant difference in terms of stress concentration could be generated between ball versus magnetic/equator versus locator attachment system due to less number of studies and conflicting results.

Conclusion

Various studies showed different results due to heterogenicity in selected attachment systems and study designs. Locator attachments showed favourable stress distribution around peri-implant bone than other attachments.

The effect of ball versus locator attachment system on the performance of implant supported overdenture: A systematic review

Objective

This systematic review was aimed to compare ball and locator attachment system on the basis of clinical and biomechanical performance of implant supported overdenture as well as biological and patient related outcomes.

Material and methods

Open and free electronic and manual searches were performed in digital databases including MEDLINE via PubMed, the Cochrane Database of Clinical Trials, and Scopus along with some other reliable sources. From the 667 retrieved records, 11 full-text controlled trials were included in this study. Risk of bias was assessed according to RoB 2.0 except for one RCT (economic evaluation), only assessed by CASP checklist.

Results

From the 11 retrieved studies, total 183 locator and 219 ball attachments were identified in 452 subjects of 30 yrs–95 yrs of age. Studies provided data about prosthodontic complications or maintenance (replacement or the activation of matrix and patrix part, loss of retention, fracture and relining of the prosthesis, fracture of the attachment and the survival probability), oral health impact profile, soft tissue parameters and periodontal complications, marginal bone loss, patient related outcome and cost of the attachment systems. Only 5 studies were assessed at low risk bias, while other 6 at moderate to high risk of bias.

Conclusion

Locator attachment system show lesser complications including loss of retention and lower maintenance appointments, lesser soft tissue, and periodontal complications than the ball attachment. Ball is better in terms of cost effectiveness. In other related outcomes, no significant differences were noted between ball and locator attachment.

Prosthetic complications and quality of life among wearers of mandibular overdenture with the Facility-Equator system

This longitudinal study aimed to assess the performance of the Facility-Equator system as mandibular overdenture (MO) retainers from a prosthetic perspective during 2 years of loading and to investigate the oral health-related quality of life (OHRQoL) and whether prosthetic events can affect the OHRQoL. Twenty-four patients (68.1 ± 7.51 years) reported their OHRQoL through the Geriatric Oral Health Assessment Index (GOHAI) and Oral Health Impact Profile (OHIP-EDENT) questionnaires before MO loading and after 1 and 2 years of usage. Prosthetic occurrences were recorded during this period. Data were analyzed using the Wilcoxon test, Mann-Whitney test, and Spearman correlation coefficients. Of the 127 prosthetic events that occurred in the first year, the most frequent events were prosthesis adjustments (16.5%), dislodgement of the Equator attachment (14.17%), and O-ring replacement (11.8%). Eighty-seven prosthetic events were recorded in the second year, the most frequent events being prosthesis adjustments (27.6%), O-ring replacement (20.7%), and recapturing the female matrix (11.5%). All domains of the GOHAI and OHIP-EDENT questionnaires exhibited a significant difference (p < 0.05) between the baseline and 1- and 2-year evaluations, except in the Social Disability and Psychological Discomfort domains (p > 0.05) of OHIP-EDENT after 1 year. Complications related to prosthetic maintenance, such as fracturing of the prosthesis, Equator dislodgement, prosthesis rebasing, and new overdenture confection, affect the OHRQoL (p < 0.05), primarily the Physical Pain and Discomfort domains, especially in the first year of MO loading.

Immediate versus Delayed Attachment Incorporation Impact on Prosthetic Aftercare among Mandibular Implant-Supported Overdenture Wearers

Background: Substantial effort is dedicated to finding the most favorable parameters that will ensure low aftercare demands among edentulous patients wearing mandibular implant supported overdentures (MISODs). The purpose of this retrospective cohort study was to compare prosthetic aftercare between MISOD patients with a simultaneous (group A) vs. a three-week settling in period (group B) prior to attachment incorporation. Methods: Forty-five patients enrolled in this study. Two implants per patient were placed using a two-stage implant insertion protocol. Second-stage surgery was performed after three months. All patients received ball attachments using the direct (chairside) incorporation method. Twenty-two patients received their dentures with simultaneous attachment activation and the rest—twenty-three patients—after a three-week settling in period. Patients’ files were scanned for aftercare visits. Outcome parameters included sore spot relief, attachment incorporation, and denture repair. Additionally, gingival index measurements were compared. Confounding factors included age, gender, and implant dimensions. Results: The mean follow-up for the entire cohort was 84 ± 21 months, and the range 39–120 months. The mean number of visits for group A vs. B respectively: pressure sores relieve (3.63 ± 0.84 vs. 3.71 ± 0.61, p = 0.581), liner exchange due to loss of retention (2.09 ± 1.03 vs. 2.31 ± 1.04 p = 0.487), and gingival index (1.3 ± 0.3 vs. 1.03 ± 0.2, p = 0.653) exhibited no statistically significant differences between the tested groups. No statistically significant differences between the groups were also noted for the denture repair aftercare treatments (p = 0.318) and the independent variables including age, gender, and implant length. Conclusions: Prosthetic aftercare in MISOD wearers is similar whether a simultaneous or a three-week settling in period for attachment incorporation is applied.

Prosthetic failures in dental implant therapy

Both fixed and removable implant‐supported prostheses are well‐established methods for replacing missing teeth in partially or fully edentulous patients. Numerous systematic reviews have been performed in recent years to evaluate the survival and complication rates of implant‐retained fixed dental prostheses and implant‐retained overdentures, displaying high 5‐year survival rates ranging from 97.1% for fixed dental prostheses to 95%‐100% for implant‐retained overdentures. However, the survival rates only represent the prostheses remaining in use for a defined follow‐up time, and do not account for the potential prosthetic complications that may have arisen and influence the general success of the implant treatment. The most common technical complications of fixed implant‐retained single crowns are crown fracture, fractures of ceramic implant abutments, and esthetic problems. The predominant technical complication at multiple‐unit, implant‐retained fixed dental prostheses is fracture/chipping of the veneering ceramic. Reported technical complications for implant‐retained overdentures are overdenture fracture or chipping of the veneer materials, whereas mechanical complications include implant fracture, attachment failure, and attachment housing or insert complications. To reduce the risk of such failures, a comprehensive pretreatment diagnostic work‐up is essential, including defining the prosthetic goal with the aid of a wax‐up or set‐up and the associated ideal, prosthetically oriented three‐dimensional implant position. Furthermore, selection of the ideal type of prosthesis, including the respective implant components and materials, is important for clinical long‐term treatment success.

Short strategic implants for mandibular removable partial dentures: One-year results from a pilot randomized crossover abutment type study

Objectives

The present pilot study analyzed two abutment types (a retentive ball and a non‐retentive dome) in implant‐assisted removable partial dentures (IARPDs) on 6 mm short implants with respect to clinical, radiological, and patient‐reported outcomes (PROs), during the first year.

Materials and Methods

Two implants were placed bilaterally in mandibular molar sites, converting existing free‐end removable partial dentures (RPDs) to IARPDs. Twelve subjects were randomized to initially receive either the dome (Group A, n = 6) or the ball abutment (Group B, n = 6). After eight weeks, the abutments were exchanged. After another 8 weeks, the participants were given the choice of one of the abutments. Mean values and standard deviations (SD) were calculated, and random‐effect linear regression analyses were applied to analyze marginal bone level alterations and PROs (α < .05).

Results

Twelve participants were included in the study; however, one dropout occurred. Patient ratings increased significantly in both study groups. The majority of the participants (82%) ultimately chose the ball abutment. The implant survival rate was 100%, and the success rate was 90.9% twelve months after implant placement (mean peri‐implant bone‐loss: −1.2; SD: 0.6 mm) without a statistically significant difference between the study groups, in terms of clinical‐ and radiological outcomes.

Conclusion

Placing 6 mm short implants at mandibular molar sites of RPD wearers seems to be a viable treatment option, based on this investigation with a short‐term follow‐up. Although only minor differences between the two abutments were observed, patients seem to prefer the ball over the dome abutment.

Implant-supported overdentures: part 1

The ability to provide high-quality complete dentures is a key skill for the GDP. The increasing prevalence and utilisation of implant-supported overdentures has opened the possibility of a wide variety of treatment options to support patient care, while also creating the need for primary care practitioners to have a greater awareness of commonly used prosthetic attachments.A thorough understanding of the advantages and disadvantages of implant-supported overdentures is essential to ensuring appropriate treatment planning, consent and maintenance. This two-part series explores various aspects of implant-supported overdentures including assessment of the patient, treatment planning, different attachment systems and maintenance requirements.Part one will explore availability of implants in the NHS, the commonly available implant attachment systems, including their relative advantages and disadvantages.

Technique for Converting A Fractured Implant Locator Abutment to A Custom Implant Cast Post and Core

This technique article describes an efficient, cost effective and time saving procedure using the fractured abutment as a custom cast post and core when an overdenture abutment is fractured and attempts to retrieve the fractured segment fail.

Prosthodontic Principles in Dental Implantology: Adjustments in a Coronavirus Disease-19 Pandemic-Battered Economy

More patients are requesting fixed prosthesis to replace missing teeth. More than 5 million dental implants are placed annually in the United States. This number will decrease in 2020 owing to the coronavirus disease-19 pandemic. The edentulous patient has a decreased quality of life. Prosthodontic rehabilitation/reconstruction of edentulism improves overall quality of life. Patient-reported outcome measures are subjective reports of patients' perceptions of their oral health status and the impact that it has on their quality of life. This chapter contains a variety of prosthodontic principles for the reader to help satisfy the needs and expectations of the patient.

Clinical outcomes of implant-retained mandibular overdentures using the bar and magnetic attachment systems: an up to 5-year retrospective study

Background

Implant-retained mandibular overdentures (IODs) represent an effective and reliable treatment modality for edentulous patients. The present retrospective study compared the clinical outcomes of IODs using bar attachment (BA) system with those using magnetic attachment (MA) system after functioning for up to 5 years.

Methods

Human subjects treated with IODs between 01-01-2010 and 12-31-2014 were identified from patient records. Of the 54 subjects who met the inclusion criteria, 48 subjects including 26 treated with BA-IODs and 22 with MA-IODs (96 mandibular implants) were recruited for the study. The implant units and prostheses were evaluated individually for peri-implant health. Prosthetic complications and maintenance during follow-up were recorded. The subjects responded to the visual analog scale (VAS) and the Oral Health Impact Profile questionnaires for evaluation of patient satisfaction and oral health-related quality of life (OHRQoL).

Results

The survival rates of the implants and prostheses were 96.9% and 95.8%, respectively, over a mean observation period of 48±11.3 (range, 13-64) months. Peri-implant probing depth (PPD) and plaque index (PI) were significantly better for the MA group compared with the BA group (P<0.05), while marginal bone loss (MBL) and sulcus bleeding index (SBI) showed no significant differences (P>0.05). Prosthetic complications and maintenance were attachment-dependent. Most recruited subjects were satisfied with their prostheses. There was no statistically significant difference regarding general patient satisfaction or OHRQoL between the two groups (P>0.05). Nevertheless, patients complained that the BA-IODs were significantly more difficult to clean than the MA-IODs (P<0.05).

Conclusions

IODs have an ideal medium-term outcome irrespective of the attachment design. It is recommended that oral hygiene instructions and regular clinical examination be given to subjects wearing IODs.

Masticatory function and oral health-related quality of life of patients with atrophic and non-atrophic mandibles using implant-retained mandibular overdentures: 3-year results of a prospective clinical study

BACKGROUND

Long-term changes in masticatory function, oral health-related quality of life (OHRQoL) and prosthetic complications in implant-retained mandibular overdenture (IMO) wearers as a function of bone atrophy require detailed investigations.

OBJECTIVE

Investigating the evolution of masticatory function, OHRQoL and prosthetic occurrences of IMO wearers according to mandibular bone atrophy over 3 years of usage.

METHODS

This study evaluated 26 IMO wearers after 2 and 3 years of IMO loading categorised according to mandibular resorption degree into atrophic mandible (AM) and a non-atrophic mandible (NAM) group. Masticatory function was assessed by the Masticatory Performance (MP) and Swallowing Threshold (ST) tests; OHRQoL and satisfaction via the Dental Impact on Daily Living (DIDL) questionnaire; and the prosthetic maintenance requirements and complications were monitored.

RESULTS

After the second year, the AM Group performed 32% more cycles (P = .047) than the NAM Group during the ST test. The DIDL questionnaire showed no significant difference for all domains, except for a moderate effect size in the General Performance domain after the third year. AM Group had more prosthetic occurrences (n = 109) than NAM Group (n = 60) in the first year, mainly due to Equator attachment dislodgment. During the third year, NAM Group presented a greater number of events (n = 45) than AM Group (n = 21) due to the greater number of O-ring exchanges.

CONCLUSION

Masticatory function and OHRQoL are not related to mandibular bone atrophy until 3 years after IMO rehabilitation. The prosthetic complications profile differs between groups, mainly in the first year.

Retrospective study comparing the clinical outcomes of bar-clip and ball attachment implant-supported overdentures

The aim of this study was to compare the clinical outcomes of implant-supported overdentures (ODs) with either bar-clip or ball attachments. The implant, prosthesis failure, and technical complications were the outcomes analyzed in this retrospective clinical study conducted in a specialty clinic. Seventy-five patients with 242 implants supported by 76 ODs (36 maxillary, 40 mandibular) were included in the study and followed up for 88.8 ± 82.9 months (mean ± standard deviation). Bar-clip and ball attachments were used in 78.9% and 21.1% of the cases, respectively. Forty-three implant failures (17.8%) in 17 prostheses (17/76; 22.4%) were observed in this study. The average period of implant failure was 43.3 ± 41.0 months, and most of them were maxillary turned implants. The bar-clip system demonstrated more complications in the attachment parts compared to the ball attachment system. Poor retention of the prosthesis was similar between the two systems. Loss of implants resulted in the failure of 10 ODs in this study. ODs opposed by natural dentition or fixed prostheses presented with more complications. The Cox proportional hazards model did not show a significant effect on prosthesis failure for any of the factors. These findings indicated that patients with ODs need constant maintenance follow-ups to address the technical complications and perform prosthodontic maintenance regardless of the attachment system used.

Attitude and treatment options in implant-supported prosthetics: A survey among a cohort of German dentists

PURPOSE

The aim of the current study was to analyze treatment concepts of a cohort of German dentists for planning, fabrication, and maintenance of implant-supported fixed and removable restorations.

MATERIALS AND METHODS

A questionnaire including queries about experiences with implant-supported restorations as well as prosthetic and maintenance treatment concepts for supplying patients with fixed and removable implant-supported prosthetic restorations was developed and sent to 350 dental offices registered in the municipal area of Leipzig, Germany.

RESULTS

An overall total of 62 returned questionnaires were included in the analyses, which relates to a response rate of 17.7%. Participating dentists were more involved in the prosthetic aspects of implant dentistry rather than surgery, while prosthetic concepts such as backward planning, digital processing, and application of all-ceramic materials were not commonly performed. Simple attachments were preferred over complex retention systems in removable implant-supported restorations. Tooth/implant-supported fixed denture prostheses as well as removable denture prostheses with supporting posterior implants were not regarded as a favorable treatment option.

CONCLUSION

Within the limitations of the study, the data indicate that dentists favor simple and conventional treatment approaches in implant prosthetics. Prosthetic aspects in the planning of implant-supported restorations are often neglected. Prosthetic treatment guidelines and aspects should commonly be considered in the planning phase of implant-supported prosthetic restorations, and awareness should be increased in postgraduate education.

Interventions for replacing missing teeth: attachment systems for implant overdentures in edentulous jaws

BACKGROUND

Implant overdentures are one of the most common treatment options used to rehabilitate edentulous patients. Attachment systems are used to anchor the overdentures to implants. The plethora of attachment systems available dictates a need for clinicians to understand their prosthodontic and patient-related outcomes.

OBJECTIVES

To compare different attachment systems for maxillary and mandibular implant overdentures by assessing prosthodontic success, prosthodontic maintenance, patient preference, patient satisfaction/quality of life and costs.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 24 January 2018); Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 12) in the Cochrane Library (searched 24 January 2018); MEDLINE Ovid (1946 to 24 January 2018); and Embase Ovid (1980 to 24 January 2018). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials on 24 January 2018. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

All randomised controlled trials (RCTs), including cross-over trials on maxillary or mandibular implant overdentures with different attachment systems with at least 1 year follow-up.

DATA COLLECTION AND ANALYSIS

Four review authors extracted data independently and assessed risk of bias for each included trial. Several corresponding authors were subsequently contacted to obtain missing information. Fixed-effect meta-analysis was used to combine the outcomes with risk ratios (RR) for dichotomous outcomes and mean differences (MD) for continuous outcomes, with 95% confidence intervals (95% CI). We used the GRADE approach to assess the quality of evidence and create 'Summary of findings' tables.

MAIN RESULTS

We identified six RCTs with a total of 294 mandibular overdentures (including one cross-over trial). No trials on maxillary overdentures were eligible. Due to the poor reporting of the outcomes across the included trials, only limited analyses between mandibular overdenture attachment systems were possible.Comparing ball and bar attachments, upon pooling the data regarding short-term prosthodontic success, we identified substantial heterogeneity (I² = 97%) with inconsistency in the direction of effect, which was unexplained by clinical or methodological differences between the studies, and accordingly we did not perform meta-analyses for this outcome. Short-term re-treatment (repair of attachment system) was higher with ball attachments (RR 3.11, 95% CI 1.68 to 5.75; 130 participants; 2 studies; very low-quality evidence), and there was no difference between both attachment systems in short-term re-treatment (replacement of attachment system) (RR 1.18, 95% CI 0.38 to 3.71; 130 participants; 2 studies; very low-quality evidence). It is uncertain whether there is a difference in short-term prosthodontic success when ball attachments are compared with bar attachments.Comparing ball and magnet attachments, there was no difference between them in medium-term prosthodontic success (RR 0.84, 95% CI 0.64 to 1.10; 69 participants; 1 study; very low-quality evidence), or in medium-term re-treatment (repair of attachment system) (RR 1.75, 95% CI 0.65 to 4.72; 69 participants; 1 study; very low-quality evidence). However, after 5 years, prosthodontic maintenance costs were higher when magnet attachments were used (MD -247.37 EUR, 95% CI -346.32 to -148.42; 69 participants; 1 study; very low-quality evidence). It is uncertain whether there is a difference in medium-term prosthodontic success when ball attachments are compared with magnet attachments.One trial provided data for ball versus telescopic attachments and reported no difference in prosthodontic maintenance between the two systems in short-term patrix replacement (RR 6.00, 95% CI 0.86 to 41.96; 22 participants; 1 study; very low-quality evidence), matrix activation (RR 11.00, 95% CI 0.68 to 177.72; 22 participants; 1 study; very low-quality evidence), matrix replacement (RR 1.75, 95% CI 0.71 to 4.31; 22 participants; 1 study; very low-quality evidence), or in relining of the implant overdenture (RR 2.33, 95% CI 0.81 to 6.76; 22 participants; 1 study; very low-quality evidence). It is uncertain whether there is a difference in short-term prosthodontic maintenance when ball attachments are compared with telescopic attachments.In the only cross-over trial included, patient preference between different attachment systems was assessed after only 3 months and not for the entire trial period of 10 years.

AUTHORS' CONCLUSIONS

For mandibular overdentures, there is insufficient evidence to determine the relative effectiveness of different attachment systems on prosthodontic success, prosthodontic maintenance, patient satisfaction, patient preference or costs. In the short term, there is some evidence that is insufficient to show a difference and where there was no evidence was reported. It was not possible to determine any preferred attachment system for mandibular overdentures.For maxillary overdentures, there is no evidence (with no trials identified) to determine the relative effectiveness of different attachment systems on prosthodontic success, prosthodontic maintenance, patient satisfaction, patient preference or costs.Further RCTs on edentulous cohorts must pay attention to trial design specifically using the same number of implants of the same implant system, but with different attachment systems clearly identified in control and test groups. Trials should also determine the longevity of different attachment systems and patient preferences. Trials on the current array of computer-aided designed/computer-assisted manufactured (CAD/CAM) bar attachment systems are encouraged.

One-year prospective clinical study comparing patient satisfaction and masticatory performance of mandibular overdentures supported by one versus two implants

There is a lack of clinical evidence on mandibular overdentures (MOD) supported by a single implant.

Comparative Study of the Fit Accuracy of Full-Arch Bar Frameworks Fabricated with Different Presintered Cobalt-Chromium Alloys

Purpose

This study was to measure the geometric discrepancies that occur during the sintering contraction of presintered Co-Cr alloys in a full-arch bar framework and to compare the variations between alloys from different manufacturers.

Materials and Methods

Eighteen implant-supported full-arch bar frameworks were fabricated through a soft-machining process using presintered Co-Cr alloy blocks: Ceramill Sintron (CS), Soft Metal (SM), and Sintermetall (SML) (n=6 for each group). The sintered frameworks were digitized using a structured light scanner, and the scan images were superimposed on the reference design. The geometric discrepancies of the sintered frameworks were three-dimensionally analyzed for horizontal, angular, and internal discrepancies. Kruskal-Wallis and Mann-Whitney U tests were used to compare the discrepancies among the groups (α=.05).

Results

Significant differences were found in the geometric discrepancy measurements among the groups. The CS group showed larger horizontal and angular discrepancies, followed by the SM and SML groups (P<.001). The root mean square (RMS) values for internal discrepancy were not statistically different among the groups (P=.778).

Conclusion

The geometric discrepancies of full-arch bar frameworks fabricated using the soft-machining process were affected by accuracies in sintering contraction of presintered alloys.