Mandibular two-implant-retained overdenture: prosthetic design and fabrication protocol

Among different treatment options, an implant-retained overdenture is a simple, cost-effective solution in the rehabilitation of the edentulous mandible. Despite widespread acceptance of this treatment, some controversies still exist with regard to the design of the overdenture, selection of the appropriate attachment system, and the most optimal techniques for the overdenture fabrication. In this article, the authors describe a mandibular overdenture retained by 2 freestanding implants placed in the anterior region of the mandible. The overdenture design includes a metal-reinforcing framework and uses prefabricated stock abutments and hinge-type resilient attachments for its retention. The proposed fabrication technique requires a minimal number of clinical appointments, and resilient attachments are incorporated into the overdenture in the laboratory.     

Clinical evaluation of overdenture restorations supported by osseointegrated titanium implants: a retrospective study

This paper reports the results of using osseointegrated titanium implants as abutments for overdenture restorations in the mandibles of 62 edentulous patients. All of these patients were edentulous for several years and required complete dentures. Six months after prosthodontic treatment, two implants (ITI, Straumann) were placed with consideration of the denture base and morphologic aspects of the mandibular residual ridge. The retention devices consisted of a bar connector or single ball-shaped precision attachments. Three or four implants splinted with a bar were placed in a control group of 11 patients. Attached keratinized gingiva (greater than or equal to 2 mm) surrounded approximately 48% of the buccal and 55% of the lingual implant sites. Evaluation after periods of 6 to 66 months postoperatively revealed good clinical results with five patients lost to recall in 1989. Two implants were lost after overdenture insertion. The findings suggest that two implants may adequately serve as retention for a mandibular complete denture and that attached gingiva surrounding the implants does not seem to be prerequisite for healthy function.     

Orientation of retentive matrices on spherical attachments independent of implant parallelism.

Traditionally, it has been advocated that implants planned for use as overdenture abutments be placed parallel to each other to obtain predictable attachment retention and complete seating of the restoration and to prevent premature wear of components. However, it is often difficult or impossible to place implants parallel to each other, and patients with implants that have already been placed in a variety of positions frequently are referred to restorative dentists. This article describes a technique for the fabrication of a matrix-paralleling device as well as 2 of its uses. The device allows proper orientation of the retentive matrices to establish a common path of withdrawal for the prosthesis and all attachments. Provided that the matrices are parallel to each other, spherical overdenture attachments can be used even when the implants are not parallel.     

A prospective evaluation of Frialoc implants with ball-abutments in the edentulous mandible: 1-year results

Several surgical and prosthetic concepts for the treatment of patients with mandibular atrophy and related lower denture problems are proposed and described in the literature. The present study discusses and evaluates the use of a new single-stage implant and overdenture with ball-attachment for this purpose. This study evaluates the clinical performance of the implants and abutments and addresses surgical and prosthetic complications that were encountered. Eighteen fully edentulous patients received two, single-stage Frialoc implants (Friadent, Mannheim, Germany). The implants were left to osseointegrate for 3 months and were subsequently provided with ball-abutments and loaded through a mandibular overdenture. After 1-year of clinical service, two implants were lost, which accumulated to a 1-year survival rate of 93.9% (SE 4.2%). Patient satisfaction was high, and prosthetic complications and postinsertion maintenance were minimal. Three abutments loosened, one of which subsequently broke after 5 months of loading. Retightening of the attachment (gold matrix) was performed on seven occasions in four patients. Soft tissue response was excellent. Although minor hypertrophy of the peri-implant mucosa was observed, hardly any marginal bone loss between baseline and 1-year observations occurred. Short-term results indicate that mandibular implant overdenture treatment by means of two ball-abutments, using Frialoc implants and prosthetic components, leads to good clinical results, both from an objective and a subjective perspective.     

A prosthetic solution to restoring the edentulous mandible with limited interarch space using an implant-tissue-supported overdenture: a clinical report

An implant-retained overdenture retained with 2 implants placed in the anterior edentulous mandible is a simple and predictable treatment option. The fabrication and use of this prosthesis requires satisfactory interarch space for adequate denture base thickness and esthetics. This clinical report describes the use of low-profile attachments for this overdenture design to solve the problem of limited interarch space.     

Solutions for Severely Angulated Implants in the Mandibular Overdenture: A Clinical Report

Results of randomized clinical trials have confirmed that implant overdentures provide patients with better outcomes than do conventional complete dentures. Several designs have been introduced for the mandibular implant-retained removable prosthesis. The most commonly used prosthesis design for the mandibular overdenture is two implants in the canine areas with a stud attachment mechanism (i.e., ball attachments). This design is the least expensive, and therefore can service more patients and is now considered to be the "Standard of Care" for the mandibular edentulous patient. Proper treatment planning and execution lead to favorable implant placement and a successful prosthetic restoration and ultimately patient satisfaction; however, implant malposition may occur, which can lead to an unsuccessful prosthesis. This clinical report describes an implant overdenture design used for severely angled implants. Prosthodontic techniques that enabled this patient to have a successful outcome included the use of cast-to attachments and abutments along with a sectional matrix used to locate these components within the bulk of the prosthesis. For this patient the prosthodontic compromises were preferred over another surgical procedure with the additional time, discomfort, increased cost, and possible surgical morbidity. It is important that the patient understand the compromises and potential problems when implant placement is not ideal, especially the potential for implant overload and failure.     

Rehabilitation of the edentulous mandible with implant-supported overdenture using ball attachments and healing abutments: A case report

For many years, osseointegrated implant-supported overdentures have been used in the rehabilitation of the edentulous lower jaw with excellent results. In this report, additional implants with healing abutments were applied posterior to mental foramen on each side was used to achieve additional support to the overdenture.     

A comparative clinical investigation of 2 early loaded ITI dental implants supporting an overdenture in the mandible

The purpose of this prospective clinical study was to evaluate the efficacy of early loading of implants and to provide evidence to support simplified treatment of mandibular edentulism by using an implant designed for 1-stage surgery, combined with ball abutments to circumvent the need for a fixed prosthodontic superstructure. Historically, the recommended time between the placement and functional loading of dental implants has been 3 months in the mandible. This recommendation is the result of a systematically chosen healing time during development of implant treatment. In recent years, histologic and experimental studies have shown that specially designed implants can result in increased bone-to-implant contact at earlier healing times. Accordingly, these implants can be placed into function faster than previously recommended. In this study, 21 patients aged between 61 and 85 years with edentulous mandibles were included. All received 2 titanium plasma-sprayed, solid-screw dental implants in the interforaminal region. Ten patients had the implants loaded with an overdenture connected with ball abutments after 3 months (control group). The other 11 patients (test group) had prostheses connected to the ball abutments after a maximum of 3 weeks. Marginal bone resorption, Periotest values, and patient satisfaction were evaluated. The cumulative post-loading implant survival rate was 100% for both groups after 24 months. Marginal bone resorption after 1 year around all implants ranged from 0 to 2 mm (no significant differences between groups; P < .05). Periotest values for all implants 1 year after loading were below zero (range -1 to -6). The results of this clinical trial suggest that successful early loading of 2 implants is possible provided there is uncomplicated implant placement.     

Technical tips for constructing a maxillary implant-supported overdenture by using a double-impression technique

Implant-supported overdentures have become a popular treatment option for completely edentulous patients. Functional loads should be optimally distributed to the mucosa and the abutments. This article describes a functional double-impression technique for fabricating a maxillary implant-supported overdenture.     

Correcting a nonparallel implant abutment for a mandibular overdenture retained by two implants: a clinical report

A mandibular overdenture supported by 2 implants is an effective treatment alternative for the maladaptive denture wearer. The implants may be either splinted, using a bar, or nonsplinted and retained by attachments, such as balls or magnets. When the use of a ball attachment is contemplated, the implant abutments should be parallel to one another along the path of insertion. The following report describes the procedure to correct a nonparallel implant abutment to retain a mandibular overdenture.     

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.
CLINICAL SIGNIFICANCE
Restoring esthetics and function for the edentulous patient requires a multidiscipline approach for success. This article discusses the techniques for restoring function and esthetics for these patients, using a milled bar restoration supported and retained by dental implants.     

The implant-supported milled-bar mandibular overdenture

Osseointegrated dental implants have been proven successful in the treatment of edentulism. The predictability of the implant‐supported prosthesis has also been established. Several techniques have been described for the successful restoration of the edentulous mandible: fixed‐detachable prostheses with either the original Brånemark hybrid prosthesis design or conventional implant‐supported fixed partial dentures, implant‐retained overdentures, and implant‐supported overdentures. However, in cases of advanced ridge resorption in which facial tissue support is needed from the flanges of the prosthesis or when a removable type of prosthesis is preferred by the patient, an implant‐supported prosthesis is indicated. Electric discharge machining is often used in the fabrication of the bar for an implant‐supported overdenture. This procedure is very costly and technique sensitive. An alternative procedure to fabricate a milled‐bar implant‐supported overdenture is described. This procedure is simple and uses inexpensive equipment and materials. The milled‐bar minimizes lateral and rotational displacement. The overdenture incorporates attachments that provide retention, minimizing possible movement along the path of insertion. This type of prosthesis is available to a broad patient population, especially those with advanced ridge resorption, providing an excellent result at a reduced cost.     

An alternative method to treat a case with severe maxillary atrophy by the use of angled implants instead of complicated augmentation procedures: a case report

Several treatment options with implants have been described for maxillary edentulous patients. Maxillary implant-supported overdentures have been shown to be a predictable, accepted treatment option for the edentulous maxilla. Patients with severe bone resorption present additional difficulties, and implant treatment in the atrophic maxilla represents a challenge. Anatomical limitations and patient desires in this case have forced the treatment to be 4 angulated implants supporting an upper overdenture. Since conventional single-retention mechanisms such as ball (O-ring), locator, or telescopes would transfer too much force to the implants, especially because of their angulation, an individual bar was fabricated. One-year follow-up of the case showed a stable peri-implant condition on bone as well as soft tissue level. Although further follow-up and higher case numbers will give more information about this treatment modality, the actual result is encouraging and can be recommended for similar cases.     

Spark erosion fixed/detachable prosthesis for the completely edentulous maxilla.

A technique is described for restoration of the completely edentulous maxilla. From six to eight root-form implants are surgically placed in the edentulous maxilla. A hybrid overdenture is constructed by use of a two-degree tapered precision milled primary bar. A cast overdenture prosthesis is constructed over this bar, and precision attachments are spark-erosion-processed to the primary and secondary prosthetic components. The technology described in this article allows for an intimate fit of the various prosthetic components. This prosthetic protocol permits maximum retention and stability of the prosthesis and solves many problems which are encountered in the oral rehabilitation of the edentulous maxilla.     

Implant-retained overdenture following hemiglossectomy: a 10-year clinical case report

summary A clinical evaluation of an implant‐supported overdenture placed in the edentulous mandible after hemiglossectomy is described. The deltopectoral flap covering the mandibular ridge was replaced with a free mucosal graft. Four Brånemark system implants were inserted into the anterior part of the mandible, but one of the four fixtures did not show osseointegration. The superstructure was designed as a spaced round bar‐attachment supported by three implants so as to retain the complete overdenture. In addition to the metal clip, a silicone‐based soft denture liner material was applied in the female portion of the attachment so as to prevent the attachment from making a clattering noise upon mastication. Although the overdenture required adjustment at regular intervals, the treatment was successful both aesthetically and functionally for up to at least 10 years.     

Osseointegration of Brånemark fixtures using a single‐step operating technique. A preliminary prospective one‐year study in the edentulous mandible.

The aim of the present prospective clinical study was to analyze the feasibility of inserting Brånemark fixtures according to a one-stage procedure including transmucosal healing and to subsequently evaluate the predictability of osseointegration as well as the potential of such implants for stabilizing complete overdentures in the edentulous mandible. Five patients (2 women, 3 men), completely edentulous in the mandible and with a mean age of 60 years, volunteered for this study. Two fixtures of various length Lpar;10–20 mm) and 3.75 mm in diameter were inserted in the lower canine regions. A standard surgical procedure including a mid-crestal incision was used. After the placement of the fixtures, healing abutments, which are normally used during second-stage surgery, were inserted instead of the usual cover screws. Three months after implant placement a clinical and radiographic examination was performed to confirm the presence or absence of osseointegration of the fixtures prior to exchanging the healing abutments with the spherical attachments. Finally, different clinical (Plaque Index, Bleeding Index, probing depth, Periotest® mobility) and radiographic (bone loss, peri-implant radiolucency) parameters were recorded 9 months after loading of the fixtures by means of a complete mandibular overdenture, retained by two ball attachments in the canine regions. All fixtures were perfectly stable (mean Periotest values of ?2) and presented favorable peri-implant soft tissue conditions, and no patient was complaining about any particular symptom. As far as retention and stability of their implant supported overdenture was concerned, the participants without exception considered the therapeutic result as being perfectly adequate. The evaluation of the radiographic analysis showed a similar initial bone loss rate as reported in the literature for a submerged surgical procedure. Therefore, within the specific limits of this study. it may be concluded that Brånemark fixtures can be inserted using a single-step surgical protocol predictably leading to successful osseointegration and subsequently provide similar peri-implant results as reported for the traditional two stage technique. However, a longer period of observation as well as a more significant number of cases will be necessary to confirm these promising preliminary data.     

An implant-supported overdenture in an edentulous upper jaw

An implant-supported overdenture is a good alternative treatment to a conventional denture for patients with complaints about the retention and stability of their removable complete denture. These complaints more often have to do with the mandibular than the maxillary denture. Implant-supported overdentures offer better results in the mandible than in the maxilla. In cases of insujficient bone volume in the maxilla for inserting implants, maxillary sinus floor elevation using an autogenous bone graft from the oral cavity or the iliac crest may be carried out. Treatment of the edentulous maxilla by inserting 6 implants followed by manufacturing a bar-clip mesostructure and an implant-supported overdenture is the most successful, followed closely by the treatment option of inserting 4 implants and fabricating a similar mesostructure and overdenture. Aftercare by routine preventive examinations is required.     

Clinical evaluation of the Biocomp-implant system. Results after 1,3 and 5 years in a general practice

A population of 107 consecutive patients was treated with a new HA-coated, screw-type dental implant (n = 384 implants), the Biocomp implant. Treatment was performed in a general dental practice by one and the same dentist. The implants were utilized for various types of prosthetic constructions, sometimes in challenging conditions with respect to patient selection, jaw bone quantity and quality. A clinical and radiographical evaluation was performed after 1, 3 and 5 years. After 5 years, the chance on implant survival was 87.1% (standard error 3.4%). Implant loss occurred predominantly within the first 1.5 year after implant placement. Particularly short implants, placed in the atrofic maxilla, frequently failed. Biocomp implants that served as abutments for an overdenture in the edentulous mandible or as a single tooth replacement in the upper anterior region had an excellent prognosis.     

The making of an overdenture supported by two endosseous implants in the lower jaw

Due to extreme alveolar resorption many edentulous patients wearing complete dentures suffer from loss of function of the orofacial system. Improvement of oral functions can be obtained by increasing the denture-support, using implants. The construction of a combined implant/mucosal supported lower overdenture will be helpful. A method to construct an overdenture on oral implants is described.     

Two-implant mandibular overdentures: simple to fabricate and easy to wear

Success rates for titanium dental implants in the anterior mandible are very high. Because of these success rates, as well as lower costs, it is common to treat edentulous patients with just 2 implants and ball anchors for retention of the overdenture, instead of 4 implants and a bar. In this paper the fabrication of 2-implant overdentures is described. In a controlled clinical trial (to be reported elsewhere), 30 subjects received a 2-implant overdenture for the mandible and a conventional prosthesis for the maxilla. The 30 control patients received conventional complete dentures for both jaws. The stability of the overdentures was excellent, and the lingual dimensions of the denture could be reduced to the level of the mylohyoid line to provide more space for the tongue. In patients with tense labial musculature or a limited amount of attached gingiva, it was important to elevate the shoulder of the implant and ball abutment above the gingival level to avoid peri-implant problems. Significantly fewer visits for adjustment related to post-placement pressure spots were required for mandibular overdentures than for conventional mandibular prostheses.