Maxillary Overdentures Research Articles

Influence of Attachment Systems on Load Transfer of an Implant‐Assisted Maxillary Overdenture

This photoelastic study compared the load transfer characteristics of 2 retention mechanisms in an implant-assisted overdenture prosthesis. Four implants were incorporated into a photoelastic model of a moderately resorbed edentulous human maxilla. Two retention mechanisms were studied by changing components on the same model and the palateless overdenture. The retention mechanisms studied were bar splint with anterior clip and distal resilient attachments, and solitary ball/O-ring attachments. Loads, ranging from 1.4 to 14.4 kg, were applied to the palatal incline of central incisors and buccal incline of premolars with and without balancing contacts. Stresses developed around all the implants under each loading condition were photographed in the field of a circular polariscope. With both retention mechanisms, protrusive and laterotrusive loads without balancing contacts caused instability of the overdenture, producing minimal stress around the implants in the supporting structure. High intensity stresses indicating intrusion of the posterior implants were noted when the bar/distal resilient attachment overdenture had balancing contacts for protrusive and laterotrusive loads. The posterior implants of ball/O-ring attachment overdenture exhibited high intensity stresses indicating not only intrusion, but also bending, when the occlusion was balanced. Balanced occlusion was required in both retention mechanisms for stability of the implant-assisted overdenture when clinically acceptable loads were applied. The protrusive and laterotrusive loads were not distributed equitably in either mechanism, since highest stresses occurred at the posterior implants.

One‐Stage Surgery and Early Loading of Three Implants for Maxillary Overdentures: A 1‐Year Report

Maxillary implant overdentures opposing mandibular two-implant overdentures are an underused treatment option for edentulous patients. Fewer implants, simple surgery, and short healing periods may increase patients' acceptance of this treatment concept. To determine implant success, after overdenture loading, of three narrow-diameter roughened-surface implants placed in edentulous maxillas, using a one-stage surgical procedure, a 12-week healing period, and opposing mandibular two-implant overdentures. Forty edentulous participants with mandibular two-implant overdentures were allocated to two groups with similar implant systems. Each group had three narrow-diameter roughened-surface implants placed into their edentulous maxillas in a one-stage surgical procedure. Standardized intraoral radiography and implant stability tests were performed sequentially at surgery, at 12 weeks (prior to loading), and at 64 weeks (after 1 year of loading with maxillary overdentures). One hundred seventeen implants were placed in 39 participants. After 1 year of loading, 15 implants had failed in 11 patients, 4 implants have been "put to sleep" in 3 patients, and 1 patient has died. Data on marginal bone loss and resonance frequency analysis showed no significant differences between the implant systems. The mean marginal bone loss was 1.30 mm (+/- 0.44 mm) from surgery to 12 weeks and 0.32 mm (+/- 0.48 mm) between 12 and 64 weeks with loading. The mean implant stability quotient and resonance frequency values showed a statistically significant improvement over time, at 56.05 (5,891 Hz), 57.54 (5,981 Hz), and 60.88 (6,167 Hz) at surgery, 12 weeks, and 64 weeks, respectively. The overall success rate for all implants combined was 81%, and the cumulative survival rate was 84.61%. In patients with mandibular two-implant overdentures, three narrow-diameter roughened-surface implants can be placed in the edentulous maxilla, using a one-stage surgical procedure, and can be loaded within 12 weeks with overdentures for 1 year.

Photoelastic analysis of the effect of palatal support on various implant-supported overdenture designs.

The effect of palatal support on various types of implant-supported maxillary overdenture designs has not been sufficiently assessed. The purpose of this study was to photoelastically evaluate the palatal support of 3 designs of maxillary implant-supported overdentures. A photoelastic model of an edentulous maxilla was fabricated with four 3.75 x 13-mm 3i implants. Three maxillary overdenture designs were fabricated: a splinted Hader bar incorporating 2 distal ERA attachments with anterior clips; non-splinted Zaag 4-mm direct abutments and attachments; and nonsplinted Locator 2-mm direct abutments and attachments. All restorative components and attachments were fitted and observed for passivity of fit and alignment. The overdentures were first tested with complete palatal coverage. Unilateral 25-lb loads were applied at the left and right first molars and the incisive papilla area. The photoelastic effects were monitored and recorded photographically. The palatal area was removed from the 3 overdentures and the loading regimens were repeated. The highest stresses under central loading were seen with the splinted Hader bar and complete palatal coverage, followed by similar levels of stress with either Zaag or Locator attachments. After removal of the palate, the center load demonstrated greater differences between designs. The highest stresses were observed with the Hader bar, followed by the Zaag and then Locator attachments. Lack of palatal coverage demonstrated higher levels of stress around implants and visible supporting tissues. The unilateral load produced the highest stress for the splinted Hader bar, followed by Locator, and then Zaag. Removal of the palatal support produced a greater effect and more concentrated stress difference for maxillary overdentures than differences between the attachment designs tested.

Photoelastic analysis of the effect of palatal support on various implant-supported overdenture designs

Statement of problem The effect of palatal support on various types of implant-supported maxillary overdenture designs has not been sufficiently assessed. Purpose The purpose of this study was to photoelastically evaluate the palatal support of 3 designs of maxillary implant-supported overdentures. Material and methods A photoelastic model of an edentulous maxilla was fabricated with four 3.75×13-mm 3i implants. Three maxillary overdenture designs were fabricated: a splinted Hader bar incorporating 2 distal ERA attachments with anterior clips; non-splinted Zaag 4-mm direct abutments and attachments; and nonsplinted Locator 2-mm direct abutments and attachments. All restorative components and attachments were fitted and observed for passivity of fit and alignment. The overdentures were first tested with complete palatal coverage. Unilateral 25-lb loads were applied at the left and right first molars and the incisive papilla area. The photoelastic effects were monitored and recorded photographically. The palatal area was removed from the 3 overdentures and the loading regimens were repeated. Results The highest stresses under central loading were seen with the splinted Hader bar and complete palatal coverage, followed by similar levels of stress with either Zaag or Locator attachments. After removal of the palate, the center load demonstrated greater differences between designs. The highest stresses were observed with the Hader bar, followed by the Zaag and then Locator attachments. Lack of palatal coverage demonstrated higher levels of stress around implants and visible supporting tissues. The unilateral load produced the highest stress for the splinted Hader bar, followed by Locator, and then Zaag. Conclusions Removal of the palatal support produced a greater effect and more concentrated stress difference for maxillary overdentures than differences between the attachment designs tested.

The Milled Bar‐Retained Removable Bridge Implant‐Supported Prosthesis: A Treatment Alternative for the Edentulous Maxilla

Restoration of the edentulous jaw with dental implants can be achieved using either an implant-supported prosthesis, such as a fixed bridge, or an implant-retained prosthesis, such as a traditional overdenture. The implant-retained prostheses use edentulous ridges as primary stress-bearing regions, and through stress-breaking mechanisms, the implants are not loaded during function. However, the success rates of maxillary overdentures do not appear to be as good as for mandibular overdentures; this may be attributable to the adverse loading conditions, short implant length, poor quality of bone, number of implants used, flexible bar design, or poor treatment planning. Many articles have also described the numerous problems and multiple visits required in maintaining a traditional bar-retained overdenture restoration, often making it more expensive in the long term than a fixed restoration. The milled bar implant-supported prosthesis offers the benefits of both fixed and removable restorations. Its infrastructure provides the same rigidity as the fixed restoration, owing to the precise fit to the superstructure, which is removable, to promote adequate access for hygiene, yet it still provides lip support and maintains close contact with the soft tissues. These advantages enhance phonetics, esthetics, correct lip support, maintenance, and patient comfort.

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.)

Treatment outcomes of fixed or removable implant-supported prostheses in the edentulous maxilla. Part II: Clinical findings

Statement of problem: There is a widespread belief that maxillary overdenture prostheses are associated with a higher frequency of complications and require more maintenance than fixed implant prostheses. Purpose: This prospective clinical study compared the treatment outcomes of fixed and removable implant-supported restorations in the edentulous maxilla with the main emphasis on the clinician’s point of view. Material and methods: Ten patients were treated with fixed screw-retained implant prostheses (group 1), and 10 patients were treated with removable implant-supported overdentures (group 2) in the edentulous maxilla. Recall was scheduled at 6-month intervals to investigate the prosthodontic treatment outcomes, including implant survival, prosthesis time until retreatment, and maintenance issues. Clinical parameters gingival index (GI), plaque index (PI), the clinical attachment level, and radiographic marginal bone levels measured, along with any biologic and mechanical complications were recorded. Results: Patients were followed over a mean period of 39 months (SD=7; group 1) and 27 months (SD=10; group 2) after implant placement. Cumulative implant survival was 97.6% for group 1 and 94.4% for group 2 after an 18-month observation period. The mean time until retreatment after prostheses insertion was 23.4 months for group 1 and 19.8 months for group 2 (n.s.). In both groups, the increase over time in the radiographically investigated bone level was found to be significant. The indices given for the mucosal health and oral hygiene status (GI and PI) were highly correlated in both groups at each recall appointment, but no significant differences were found between groups 1 and 2. Conclusion: In groups 1 and 2, comparable prosthodontic treatment outcomes were achieved. The majority of mechanical complications could be managed chairside during recall visits and did not require additional appointments, so that the time and costs involved in providing maintenance were kept down. (J Prosthet Dent 2000;83:434-42.)

A clinical and radiological two‐year follow‐up study of maxillary overdentures on osseointegrated implants

In order to satisfy the need to restore the aesthetics, phonetics and comfort and to facilitate optimal hygiene procedures, 20 edentulous patients were treated with a new concept of overdenture therapy on implants and modum Brånemark. After 24 +/- 3.5 months the patients were re-examined. They were asked to answer a questionnaire and use a Visual Analogue Scale (VAS) to give their opinion on the prosthetic treatment. The results indicate that an implant-retained overdenture in the maxilla with this design can satisfy the patients needs in aesthetics, phonetics and comfort and can facilitate oral hygiene measures.

Failures and complications in 92 consecutively inserted overdentures supported by Brånemark implants in severely resorbed edentulous maxillae

Overdenture treatment for the atrophic maxilla was evaluated in this retrospective clinical study. Brånemark fixtures were placed in the maxillae of 92 patients who presented with compromised bone quality or quantity. A maximum number and length of implants were placed; however, 70 percent of the fixtures were 7 mm. The prosthetic treatment consisted of the conversion of an existing denture or the fabrication of a new overdenture. Patients were followed for 1 year postinsertion. There was a failure rate of 6.3 percent for implants prior to overdenture insertion. The rate of failure of implants during the first year of loading was 9.8 percent and these failures resulted in complete prosthetic failure in 7.6 percent of overdentures. The authors related the relatively high incidence of failure to the unfavorable bone and large number of 7-mm implants used in this study. The most common prosthetic complications were fracture of the retentive clip (22 percent) or acrylic resin (11 percent). More extensive postinsertion maintenance was needed for maxillary overdenture treatment as compared with maxillary implant-supported fixed prostheses.

Application of silica coating technique for removable prosthodontics. A clinical report

A technique for constructing a maxillary removable partial overdenture using the Silicoater system has been described.

Preventing fractures of maxillary overdentures

Preventing fractures of maxillary overdentures

Bruxism in maxillary overdenture patients

Bruxism in maxillary overdenture patients

A two-year longitudinal study of the periodontal health status of overdenture patients

Eleven patients who were treated with maxillary or mandibular overdentures or both were recalled at 6-month intervals and studied for a period of 2 years A periodontist evaluated the periodontal health status of the abutment teeth at initial placement of the overdenture and at all subsequent recalls using standardized periodontal indices. Statistical comparisons of the data from initial examination to the 2-year recall were made to assess the periodontal health status of roots supporting overdentures. Periodic, regular recall of patients treated with overdentures is one of the most important factors in the maintenance of the integrity of the root stumps and attachment apparatus, particularly since the roots supporting mandibular overdentures are at greater risk periodontally than those supporting maxillary overdentures. Measurements of pocket depth and width of attached gingivae seem to be the most definitive criteria to determine the status of the attachment apparatus in overdenture patients. With frequent recall, overdentures appear to be a successful method of treatment.

Immediate overdenture

An immediate complete maxillary overdenture is fabricated for a patient whose remaining maxillary teeth have been treated endodontically. The rationale for and description of the fabrication of a maxillary immediate overdenture are given. Amalgam is used to restore the endodontically treated, retained roots. This procedure decreases the cost of the treatment and makes this service available to more patients. An immediate complete maxillary overdenture is fabricated for a patient whose remaining maxillary teeth have been treated endodontically. The rationale for and description of the fabrication of a maxillary immediate overdenture are given. Amalgam is used to restore the endodontically treated, retained roots. This procedure decreases the cost of the treatment and makes this service available to more patients.