Implant-retained Maxillary Overdentures Research Articles

Incidence of peri-implant mucositis and peri-implantitis in patients with a maxillary overdenture: A sub-analysis of two prospective studies with a 10-year follow-up period.

BackgroundThough studies on maxillary overdentures show satisfying results on implant survival, patient‐related outcomes and prosthetic complications, the epidemiology of peri‐implant diseases in this specific group of patients has hardly been reported. While the general patient‐level prevalence of peri‐implant mucositis and peri‐implantitis are estimated at ~45% and ~20%, respectively, the risk of developing these diseases within a specific period is less clear. To fully appreciate the epidemiology of peri‐implant diseases, more long‐term data on incidence of peri‐implant diseases are needed.PurposeThe purpose of this sub‐analysis of two prospective studies was to assess the incidence of peri‐implant mucositis and peri‐implantitis in fully edentulous patients with implant‐retained maxillary overdentures during a 10‐year follow‐up period.Materials and MethodsOne hundred and sixteen patients treated with implant‐supported maxillary overdentures were available from two clinical trials. Data on biological complications, clinical and radiographical parameters were collected for 106 patients at 5‐year, for 82 patients at 10‐year follow‐up. The incidence was calculated following the consensus of the 2017 World Workshop on the Classification of Periodontal and Peri‐Implant Diseases and Conditions. Extent and severity then were calculated to enable an appropriate epidemiological description of peri‐implantitis.ResultsThe patient‐level incidence of peri‐implant mucositis was 37.7% after 5 years and 64.6% after 10 years whereas the patient‐level incidence of peri‐implantitis was 10.4% after 5 years and 19.5% after 10 years. After 10 years, the extent of peri‐implant mucositis and peri‐implantitis is 52.8% and 43.8%, respectively. In terms of severity, 26.5% of all affected implants suffered from >3 mm bone loss and 17.6% of all affected implants was lost.ConclusionThree of five fully edentulous patients with implant‐supported maxillary overdentures experience peri‐implant mucositis after 10 years. Peri‐implantitis occurs in one of five patients after 10 years. In spite of these incidence rates, implant survival remains high.

How successful are maxillary implant-retained overdentures on two or four implants?

Design A randomised crossover clinical trial was designed to determine survival and success of four-implant overdentures in the edentulous maxilla, in participants with mandibular two-implant overdentures. Participants received four implants in the maxilla, two anteriorly and two posteriorly, then were randomly allocated into two treatment groups. The prosthetic phase included alternate loading of anterior and posterior implants for three months each, followed by loading of all four implants for another three months. Participants were then followed up in the recall phase for a mean period of 2.2 years.Case selection Four participants were taken from the authors' previous clinical study, meeting the inclusion criteria for a two-implant overdenture in the mandible. Another 21 participants were recruited from study calls after a widening of inclusion criteria. These patients were all pre-treated in accordance with the previous study protocol, so there was standardisation before maxillary implant placement.Data analysis A sample size calculation was performed and a Kaplan-Meier curve was used to demonstrate implant survival over time.Results Twenty-four patients were included in the study. Three implants were lost during the prosthetic phase and two during the recall phase; all were anterior implants. Implant survival after loading was 93.8% after a mean period of 3.1 years. There were 27 maxillary prosthetic complications overall. Denture success was 95.8% after a mean period of 2.2 years.Conclusions Implant survival of four asynchronously loaded implants in implant-supported overdentures in the edentulous maxilla was good and is a recommendable treatment option for patients with two-implant mandibular overdentures. Implant and prosthetic complications are common but mostly straightforward to manage. Two posterior implants are not superior to two anterior implants, but the majority of patients prefer the four-implant maxillary overdenture.

Effect of Osseodensification Implant Site Preparation Technique on The Primary Stability of Implant Retained Maxillary Overdentures

Effect of Osseodensification Implant Site Preparation Technique on The Primary Stability of Implant Retained Maxillary Overdentures

Finite Element Analysis (FEA) of Palatal Coverage on Implant Retained Maxillary Overdentures

Purpose: The aim of this study was to determine stress levels on supporting structures of implant-retained overdentures as a function of varying degrees of palatal coverage using finite element analysis modeling at different loading angles. Materials and Methods: ABAQUS®-software was used to perform finite element analysis on eight overdenture models with three and four implants and with and without palatal coverage designs. Loads were applied perpendicular and 45º to the implants. Von Mises stress was measured to determine bone stress. A one-way ANOVA determined which model caused the most stress to the maxillary bone. Results: Palatal coverage increased stress to anterior implant in three implant (p = 0.08) models but decreased stress to all implants in four implant models (p = 0.43). Distal implants received more stress than anterior implants for all models. There was no significant difference between a full palate and no palate coverage overdenture prosthesis when a bar was added under axial loading (p = 0.954). Under non-axial loading, a decrease in stress was noted with the bar in all areas except the anterior implant site. Conclusions: Palatal coverage may not be necessary when applying a pure axial load. The addition of a bar decreased stress at loading.

Full-Mouth Rehabilitation With Implant-Prosthesis in Marfan Syndrome Patient: Clinical Report and Literature Review

The purpose of this case report is to present implant-retained maxillary and mandibular complete overdentures in a patient with Marfan syndrome. The patient initially presented with generalized periodontitis (stage IV, grade C). Due to the progressive nature of periodontal disease, the patient elected to have implant-retained maxillary and mandibular complete dentures. Bilateral maxillary sinus augmentation was performed 6 months before full-mouth extraction, alveoloplasty, and immediate implant placement. Maxillary and mandibular immediate overdentures were delivered. After 4 months of healing, the final overdenture was fabricated. The patient was seen regularly throughout the healing process for peri-implant maintenance. Soft-tissue grafts were completed to increase the thickness of the mucosa around the implants. The patient has been followed for 2 years and is functioning well without major complications. For patients with Marfan syndrome, implant-retained prostheses are a viable treatment option in the presence of a failing dentition.

Retrospective cohort analysis of maxillary overdentures retained by unsplinted implants

Statement of problemImplant therapy involving an unsplinted 2-implant–retained overdenture is well defined as a successful treatment for a patient with an edentulous mandible. However, a similar unsplinted implant therapy supporting a maxillary overdenture is not well characterized. PurposeThe purpose of this retrospective study was to evaluate maxillary overdentures retained by 4 unsplinted implants measuring implant survival, overdenture survival, and patient-reported outcomes. Material and methodsParticipants who had received an unsplinted implant-retained maxillary overdenture were included in the study. Participants presented for one denture recall appointment, during which comprehensive examination, including radiographs, was performed and clinical findings were recorded. Participants also completed the Oral Health Impact Profile-49 (OHIP-49) and a 20-item visual analog scale (VAS) satisfaction questionnaire. Nonparametric statistical tests were used to compare OHIP-49 and VAS scores across age, sex, time since overdenture insertion, mandibular dental status, smoking status, maxillary mucosal health, and overdenture hygiene. ResultsFor the 44 participants, 3 of 4 implants failed in 1 individual. The cumulative implant survival rate was 98% (97.7% patient level). No prosthetic failures (that is, overdenture replacement) occurred, indicating a 100% prosthesis survival rate. The mean ±standard deviation OHIP-49 severity score was 23.6 ±26.0, and the mean ±standard deviation total VAS score was 179.2 ±29.4. Increased age was associated with lower OHIP-49 severity score (P=.036), and participants with unhealthy oral mucosa or denture stomatitis demonstrated significantly higher OHIP-49 severity scores (P=.003). ConclusionsIn this retrospective evaluation, unsplinted implant-retained maxillary overdenture therapy was associated with high implant and prosthetic survival, as well as high patient satisfaction and quality of life. Age, sex, maxillary mucosal health, and mandibular dental status resulted in significant differences with respect to oral health–related quality of life and patient satisfaction, indicating that this treatment option may be ideal for certain patients.

Patient-Reported Outcomes of Maxillary Edentulous Patients Wearing Overdentures Retained by Two Implants from Insertion to 4 Years.

This cohort study evaluated patient satisfaction for maxillary implant-retained overdentures (IODs) on two implants up to 4 years and assessed the treatment effect over time. Patients encountering problems with their conventional dentures were included and received maxillary IODs on two titanium-zirconium implants and ball anchors in the canine area. Patient satisfaction was assessed using the oral health impact profile (OHIP-20E) questionnaires both for dentures and IODs. Two months after insertion of IODs (baseline), the patients chose the preferred overdenture design with full or reduced palatal coverage. OHIP-20E questionnaires were followed according to the individual choice at 1 and 4 years, and outcomes were compared with baseline. Sixteen out of 21 patients were evaluated at a mean follow-up of 4 years (range: 2.4 to 4.8 years). There was no significant difference in the OHIP domains for IODs at 1 year (OHIP_total_1y: 9.5, SD: 13.0) and 4 years (OHIP_total_4y: 14.2, SD: 19.1) compared with baseline (OHIP_total_BL: 12.4, SD: 14.7). Patients were most satisfied with social disability both for IODs (OHIP_BL: 6.0, SD: 7.6; OHIP_1y: 3.4, SD: 5.4; OHIP_4y: 5.7, SD: 9.5) and dentures (OHIP_CD_old: 28, SD: 29.7; OHIP_CD_new: 25.4, SD: 28.67). Patients were least satisfied with functional limitation both for IODs (OHIP_BL: 6.0, SD: 7.6; OHIP_1y: 3.4, SD: 5.4; OHIP_4y: 5.7, SD: 9.5) and dentures (OHIP_CD_old: 28, SD: 29.7; OHIP_CD_new: 25.4, SD: 28.67). Patient satisfaction with maxillary IODs on two implants did not change from baseline to 4 years and was high at 4 years of function.

Effect of Different Bar Designs on Axial and Nonaxial Retention Forces of Implant-Retained Maxillary Overdentures: An In Vitro Study

This in vitro study aimed to evaluate and compare the effect of different bar designs on the retention forces of implant-retained maxillary overdentures. A maxillary edentulous acrylic resin model without alveolar undercut was fabricated. Four implant analogs were placed in the canine and second premolar regions. Overdentures were made and attached to the analogs with Dolder bar, Hader bar, and milled bar attachments. A universal testing machine was used to measure axial (resistance to vertical displacement) and nonaxial (resistance to anterior, posterior, and lateral displacement) retention forces (in Newtons). Measurements were made at the start of the experiment (initial retention) and after 540 cycles of denture insertion and removal to simulate 6 months of clinical function (final retention). Hader bar had the highest retention after insertions and removals, and Dolder bar had the lowest retention. Vertical displacement showed the highest retention for Dolder and milled bars, and posterior displacement showed the highest retention for Hader bar. Lateral displacement recorded the lowest retention for all bar designs. No significant difference in axial retention loss was observed between different bar designs. Dolder bar showed the highest nonaxial retention loss, and milled bar showed the lowest retention loss. Hader bar is recommended to retain maxillary implant overdentures, as it was associated with higher axial and nonaxial retention compared with Dolder and milled bars after 6 months of simulated denture wear.

Serie: Hora est. De overkappings­prothese in de bovenkaak: op een staafmesostructuur of locators?

An overdenture on implants is the treatment of choice for patients with complaints about their conventional complete dentures. While a lot is known regarding the performance of implant-supported mandibular overdentures, much less is known regarding the performance of implant-retained maxillary overdentures. In this doctoral dissertation, various aspects of overdentures on 4 dental implants in the maxilla are discussed. From a systematic review of the literature, it appeared that an overdenture (maxillary or mandibular) on implants improved chewing efficiency, increased maximum bite force and increased patient satisfaction. Implants placed with a maximum dehiscence of two thirds of the buccal implant surface also appeared to function well after 5 years. An overdenture with a bar attachment system was associated with less marginal bone loss, a better subjective chewing efficiency and greater patient satisfaction than an overdenture retained by locators. The differences were, however, small and from a cost-effectiveness point of view, the use of overdentures retained by locators would not be a bad choice.

Effect of different processing techniques of denture bases on the supporting structures of maxillary implant retained overdentures

Objectives: This study was conducted to evaluate the effect of two different processing techniques of denture bases on bone height changes in implant retained maxillary overdenture.Materials and methods: Fourteen completely edentulous patients were recruited to participate in this study. Inclusion criteria: These patients had adequate bone in the maxillary arch to receive four hybrid implants, exhibited angle class I ridge relationship and adequate inter-occlusal space. Exclusion criteria were: V shaped edentulous ridges, patients with neuromuscular diseases and temporomandibular joint disorders, diabetic and smoking patients. Patients were randomly divided into two groups. Group I: Seven patients received a maxillary implant retained overdenture fabricated from (PMMA) base processed by the compression mold technique. Group II: Seven patients received maxillary implant retained overdenture fabricated from thermoplastic biocompatible base processed by the injectable mold technique. All patients received conventional mandibular complete dentures. Bone height around dental implants was measured after insertion, 6 months, and 12 months post-insertion.Results In this study, bone height changes around dental implants for group I and group II at the first follow up period were 0.56 mm and 0.49 mm respectively, however, at the 2nd follow up period (6-12 months), they were 0.41mm and 0.34 mm consequently. There were no statistically significant differences between the studied groups regarding the average bone loss around the dental implants as as shown by independent t-test.Conclusion Injection and compression molded processing techniques have similar effects on bone height changes in maxillary implant-retained overdentures.

Comparative study of splinted and unsplinted implant-retained maxillary overdentures without palatal coverage: A literature review

The palatal coverage is considered as an auxiliary element in the distribution of tensile strains on implant maxillary total prosthesis (implant overdentures) bases, either implant-supported or retained. However, complaints in some patients due to palate and phonetic impairment are constant. The palatal coverage removal would allow the improvement of these issues as well as pharyngeal control, salivary flow and hygiene. Thus, this literature review proposed to analyze the survival rates of dental implants retaining an implant maxillary overdenture without palatal coverage in edentulous maxilla. The review was conducted in Medline database, via PubMed between 2000 to 2016 period, and limited to English language publications. The search strategy took the following key-words, referencing title and / or abstract: dental implants; maxilla; maxillary; overdenture; and palatal coverage. According the data, the rehabilitation of the maxillary edentulous with four implant-supported overdentures with bar attachments and implant-retained with ball attachments has shown great survival rates of dental implants, but there are a few studies reporting the survival rate of implant overdentures. It was concluded that the prosthetic rehabilitation of total maxillary edentulous patients is viable through palateless implant overdentures when a minimum of four to six implants were used with careful planning and execution. KeywordsDental Implants; Maxilla; Overdenture and Palatal coverage.

Maxillary implant-supported overdentures opposed by (partial) natural dentitions: a 5-year prospective case series study.

The aim of this study was to assess the 5-year treatment outcome of maxillary implant-retained overdentures opposed by natural antagonistic teeth. Fifty consecutive patients received maxillary overdentures supported by six dental implants. Implants were placed in the anterior region, if enough bone was present (n = 25 patients) Implant were placed in the posterior region if implant placement in the anterior region was not possible (n = 25 patients). Variables assessed included survival of implants, condition of hard and soft peri-implant tissues and patients' satisfaction. The five-year implant survival rate was 97·0% and 99·3%, and mean radiographic bone loss was 0·23 and 0·69 mm in the anterior and posterior group, respectively. Median scores for plaque, calculus, gingiva, bleeding and mean scores for pocket probing depth were low and stayed low. Patients' satisfaction after treatment was high in both groups. Within the limits of this 5-year study, it is concluded that six dental implants (placed in the anterior or posterior region) connected with a bar and opposed to natural antagonistic teeth result in acceptable results for clinical parameters and good outcomes for marginal bone level changes and patient satisfaction.

Retentive Properties of O-Ring and Locator Attachments for Implant-Retained Maxillary Overdentures: An In Vitro Study.

To evaluate and compare retentive properties of O-ring and Locator attachments for implant-retained maxillary overdentures. Four implant analogs were inserted in canine and second premolar areas of an acrylic edentulous maxillary model. A metal-reinforced experimental acrylic overdenture was constructed and connected to the analogs using either O-ring (group I) or Locator (group II) attachments. Locators were divided into 3 subgroups according the degree of retention of the patrix nylon insert: Locator extra-light retention (group IIa), Locator light retention (group IIb), and Locator medium retention (group IIc). Vertical and oblique (lateral, anterior, and posterior) dislodging forces were measured at the beginning of the study (initial retention) and after 540 cycles of denture insertion and removal (final retention). For vertical, lateral, and anterior dislodging, group IIc recorded the highest initial and final retention, and group I recorded the lowest retention. For posterior dislodging, group I recorded the highest retention, and group IIa recorded the lowest retention. For group II, vertical dislodging recorded the highest initial and final retention, and lateral dislodging recorded the lowest retention. For group I, posterior dislodging recorded the highest initial and final retention, and lateral dislodging recorded the lowest retention. For all dislodging forces (except posterior dislodging), the highest retention loss was recorded in group I, and the lowest retention loss was recorded in group IIa. Locator medium attachment was associated with favorable retention during axial (vertical) and nonaxial (anterior and lateral) dislodging compared to other types of Locator inserts and O-ring attachments after a simulated 6-month period of overdenture use.

Finite element analysis on stress distribution of maxillary implant-retained overdentures depending on the Bar attachment design and palatal coverage.

PURPOSEThe purpose of this study was to determine the effect of anchorage systems and palatal coverage of denture base on load transfer in maxillary implant-retained overdenture.MATERIALS AND METHODSMaxillary implant-retained overdentures with 4 implants placed in the anterior region of edentulous maxilla were converted into a 3-D numerical model, and stress distribution patterns in implant supporting bone in the case of unilateral vertical loading on maxillary right first molar were compared with each other depending on various types of anchorage system and palatal coverage extent of denture base using three-dimensional finite element analysis.RESULTSIn all experimental models, the highest stress was concentrated on the most distal implant and implant supporting bone on loaded side. The stress at the most distal implant-supporting bone was concentrated on the cortical bone. In all anchorage system without palatal coverage of denture base, higher stresses were concentrated on the most distal implant and implant supporting bone on loaded side.CONCLUSIONIt could be suggested that when making maxillary implant retained overdenture, using Hader bar instead of milled bar and full palatal coverage rather than partial palatal coverage are more beneficial in distributing the stress that is applied on implant supporting bone.

The effect of number and distribution of unsplinted maxillary implants on the load transfer in implant-retained maxillary overdentures: An in vitro study

There is little information as to how the number and distribution of implants affect the amount of load transmitted to the palate in implant-retained maxillary overdentures. The purpose of this study was to evaluate the effect of the number and distribution of dental implants on the load transmitted to the palate. Eight implant analogues were placed in a replica of an average sized edentulous maxilla corresponding to the position of canines, first and second premolars, and first molars. The anteroposterior distance between the centers of implants in each quadrant was 8 mm. Fifteen denture bases were fabricated to fit the edentulous maxilla analogue. The denture bases were attached to the oral analogue using 6 different configurations of attachments (6 groups): Either no Locator attachments were used (control group), or the 2 most anterior attachments were attached, or 4 implants were engaged with a distance of 8, 16, or 24 mm between the centers of implants on left and right side, and finally, when all 8 attachments were activated. A force-measuring sensor was used to measure the force transmitted to the palate when a static force of 245 N was applied on the occlusal rims of the denture bases. Data (Newtons) were analyzed using 1-way ANOVA and Tukey's HSD test α=.05). The mean (SD) amount of force measured on the palate when the overdentures were supported by 4 Locator attachments; [49.84 (26.52) at 8 mm spacing], [24.42 (15.05) at 16 mm spacing], [35.66 (22.94) at 24 mm spacing] was significantly lower than when no attachments [90.98 (20.20), control], or when 2 Locator attachments were used [76.07 (27.63)] (P<.001). When the overdentures were supported by 8 Locator attachments, the force measured on the palate [20.67(16.06) N] was significantly lower than that for the control group (P<.001), overdentures supported by 2 Locator attachments (P<.001), and overdentures supported by 4 Locator attachments when the distance between the anterior and posterior implants was 8 mm P=.006). The distribution of implants had a significant effect on the force measured on the palate of the oral analogue in overdentures retained by Locator attachments. When the distance between the 4 implants was 16 or more mm, the load was not significantly lower than the 8 implant design, suggesting that the palate of a 4 implant-retained overdenture with a distance of 16 mm or more, does not contribute significantly to the load transfer to underlying hard palate in the in vitro analogue evaluated.

An Implant-Retained Maxillary Overdenture to Obturate a Patent Oronasal Communication: A Case Report

This is a case report of dental prosthetic treatment of a 72-year-old patient with cleft palate with a persisting oral nasal communication in the anterior hard palate. The remaining teeth were extracted, and dental implants were surgically placed in the maxilla and mandible to retain removable overdentures. The maxillary complete overdenture had full palatal coverage as opposed to partial coverage. It was retained by 5 implants with low-profile light retentive retainers. The mandibular overdenture was retained with 4 implants of different diameters and brands. Apparent parameters for successful treatment of a removable maxillary overdenture are as follows: denture flanges, flat or lingualized occlusal scheme, light low-profile retainer retention, maximum implant positional spread with parallel placement, and a minimum of 4 rough-surfaced, long, wide implants placed in denser-type bone sites.

Palatal Mini-Implants to Increase Retention and Stability of Implant-Retained Maxillary Overdentures: A Case Report

Maxillary edentulous patients have been successfully treated with implant-supported fixed and removable dental prostheses. The fixed implant-supported dental prosthesis has been used for >20 years. It has lost popularity because the design of this restoration requires special access for oral hygiene around the abutment cylinders creating an esthetic quandary in the maxilla. The use of the mid-sagital palatal suture to osseointegrate anchorage devices for orthodontic purposes has shown satisfactory results. This clinical case documents the successful use of mid-palatal implants as an extension of orthodontic anchorage to gain accessory support and retention for a maxillary complete removable dental prosthesis.

Alternate functional impression technique for implant-retained overdentures

An overdenture impression must record the soft tissue supporting areas simultaneously with accurate positioning of the implant components. 1 Hussaini S. Wong T. One clinical visit for a multiple implant restoration master cast fabrication. J Prosthet Dent. 1997; 78: 550-553 Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar Three types of impression techniques have been described in the literature. A single-stage impression procedure is commonly used with either an open or closed tray technique. 2 De La Cruz J.E. Funkenbusch P.D. Ercoli C. Moss M.E. Graser G.N. Tallents R.H. Verification jig for implant-supported prostheses: a comparison of standard impressions with verification jigs made of different materials. J Prosthet Dent. 2002; 88: 329-336 Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar , 3 Ganddini M.R. Schejtman N. Ercoli C. Graser G.N. Prosthodontic application for implant carriers. J Prosthet Dent. 2004; 92: 399-402 Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar A double-impression technique for overdentures retained by only 2 implants has been suggested, using a zinc oxide eugenol (ZOE) impression paste and polyether impression material. 4 Mericske-Stern R.D. Taylor T.D. Belser U. Management of the edentulous patient. Clin Oral Implants Res. 2000; 11: 108-125 Crossref PubMed Google Scholar The third type of impression technique is a functional impression technique for implant-retained overdentures. 5 Uludag B. Sahin V. A functional impression technique for an implant-supported overdenture: a clinical report. J Oral Implantol. 2006; 32: 41-43 Crossref PubMed Scopus (3) Google Scholar Double and functional impression techniques are not considered for overdentures retained by more than 2 implants. 4 Mericske-Stern R.D. Taylor T.D. Belser U. Management of the edentulous patient. Clin Oral Implants Res. 2000; 11: 108-125 Crossref PubMed Google Scholar , 5 Uludag B. Sahin V. A functional impression technique for an implant-supported overdenture: a clinical report. J Oral Implantol. 2006; 32: 41-43 Crossref PubMed Scopus (3) Google Scholar , 6 Uludag B. Celik G. An alternative impression technique for implant-retained overdentures. J Prosthet Dent. 2006; 96: 377-378 Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar An implant-retained overdenture has characteristics resembling those of a complete denture, with a combination of tissue support and implant retention. 4 Mericske-Stern R.D. Taylor T.D. Belser U. Management of the edentulous patient. Clin Oral Implants Res. 2000; 11: 108-125 Crossref PubMed Google Scholar Thus, resilience difference between implant and mucosa should be considered for the impression of implant-tissue-retained overdentures. 6 Uludag B. Celik G. An alternative impression technique for implant-retained overdentures. J Prosthet Dent. 2006; 96: 377-378 Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar The functional impression technique records the mucosa in a functional state and simultaneously records the implant components in relation to the alveolar tissues. The primary advantage of this technique is to provide the accurate relation of the implant components and the supporting tissues. After insertion of the prosthesis, chair time decreases for postinsertion adjustments. 5 Uludag B. Sahin V. A functional impression technique for an implant-supported overdenture: a clinical report. J Oral Implantol. 2006; 32: 41-43 Crossref PubMed Scopus (3) Google Scholar However, the procedure is technique sensitive in recording the border relation with different impression materials, and it is more time consuming compared with the single-stage impression. This article describes an alternative functional impression technique to fabricate implant-retained maxillary overdenture with a bar design.

Retention of maxillary implant overdenture bars of different designs

Statement of Problem. The specific degree of retention for overdenture attachments is unknown in relation to design, location, and alignment to supporting dental implants. Purpose. The purpose of this study was to evaluate the initial retention characteristics of 5 implant maxillary overdenture designs under in vitro dislodging forces. Material and Methods. A simulated edentulous maxilla was fabricated with 4 screw-type 3.75 × 13-mm implants anteriorly. Five overdenture designs with the following attachments were evaluated: 4 plastic Hader clips with an EDS bar; 2 plastic anterior Hader clips with an identical EDS bar; 2 Hader clips with 2 posterior ERA attachments; 3 Zaag attachments on a bar; and 4 Zaag attachments with no bar. Overdentures were fabricated with full palatal coverage. Each design was subjected to 10 consecutive retention pulls on a universal testing machine. Data were subjected to analysis of variance and t tests to determine differences. Results. The highest average value after 10 pulls was 19.8 lb for the combination ERA and Hader clip design. The lowest retentive values were recorded for the 2 and 4 Hader clip designs (5.08 ± 0.89 lb and 5.06 ± 0.67 lb, respectively). Retention decreased over the course of consecutive pulls for all designs, especially for the most retentive designs. The smallest retention decrease occurred with the least retentive designs. Conclusion. The results of this in vitro study suggest that the precise selection and placement of attachments may affect the clinical success of maxillary implant-retained overdentures. (J Prosthet Dent 2001;86:603-7.)