Retention and load transfer characteristics of implant-retained auricular prostheses

PURPOSE: The use of osseointegrated implants for maxillofacial prostheses reduces the need for adhesives, provides for a more stable and more esthetic prosthesis with thinner margins, and results in increased patient acceptance and confidence. The purpose of this study was to compare the retention and load transfer characteristics of differently designed implant-retained auricular prostheses. MATERIALS AND METHODS: A photoelastic model was fabricated of the auricular-temporal region of a human skull. Craniofacial implants 3.75 mm in diameter and 4 mm long were embedded in locations typically selected to retain auricular prostheses. Two retention mechanisms were evaluated on the implants: a Hader bar with 3 clips and the use of 3 Locator attachments. The retentive capacity of the prostheses was determined on an Instron test machine. Initial retention and changes with multiple removals were examined. Dislodgment forces were applied to each retentive device in the field of a circular polariscope. Resulting stresses were monitored and recorded photographically. RESULTS: The highest initial retention demonstrated by the Locator device was 12.4 +/- 0.9 lb, and the highest retention value for the Hader bar with clips was 7.5 +/- 1.1 lb. All attachments decreased in retention after multiple removals. The Locator devices produced higher peri-implant stresses compared to the Hader bar-with-clips design. CONCLUSIONS: Since higher retention is associated with higher stresses, results of this study suggest that a balance between retention and stress production is necessary in selecting a retention mechanism for the specific requirements of the patient being treated. The Locator attachment was correlated with higher retention values as well as with higher peri-implant stress compared to the Hader bar-and-clip attachment design. Retention decreased and then stabilized after multiple     

种植体与杆卡式附着体用于义耳修复

将３只骨融合式螺旋种植体植入耳缺损区，采用杆卡式附着体作为种植上的部结构和义耳的固体装置，解决义耳固位，这种固位方式具有固位可靠，取戴方便，便于自洁，利于局部组织健康等优点，特别是在对抗侧向力方面具明显的优越性，是目前义耳修复最佳的固位方式。     

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 x 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.     

Framework night guards for implant-retained auricular prostheses

Prosthetic ear rehabilitation with osseointegrated implants involves using a cast or preformed framework (bar) constructed to fit the implant abutments. Retention of the prosthesis is obtained through clips or magnets. Because the prosthetic ear is not worn during sleep, the ends of the retention bar are left exposed. These projections may become entangled with the linen or hair. To prevent this problem a night guard constructed of soft mouth-guard material is worn over the retentive bar while the patient is sleeping.     

Comparative study of retentive anchor systems for overdentures.

OBJECTIVES: This study aimed to evaluate the retention on two or four implants of eight resilient and nonresilient retentive anchors used in overdentures. METHOD AND MATERIALS: Eight groups of retentive anchors were used: Dyna and Shiner (magnets); Dalla Bona and O-Ring (balls); Ceka Revax and Zaag attachments (studs); the cast bar (Dolder type) system with plastic clips; and the milled bars system. These specimens with their respective overdentures were prepared on two similar acrylic resin models with four implants (3.75 x 13 mm). Ten tensile strength tests (Instron) were performed on each group at a speed of 3 mm per minute. The statistical analysis (one-way analysis of variance, Tukey's HSD test) was considered significant. RESULTS: The pull force values ranged between 0.400 and 3.800 daN (International System of Units). There was a significant difference in retention in favor of the milled bars in comparison with the Ceka Revax, Hader bars, Zaag attachments, O-Ring, and Dyna groups, and a marginally significant difference compared with the Dalla Bona group. There was a highly significant difference with the Shiner magnets. CONCLUSION: The milled bar system was the most retentive anchor, with the Dalla Bona, Ceka Revax, Hader Bar, Zaag attachment, and O-Ring groups being the second most retentive. The least retentive groups were the Shiner and Dyna magnets. Proper abutment placement in the mandible and the correct selection of the retentive anchor will improve overdenture retention.     

The influence of interimplant distance and attachment type on the retention characteristics of mandibular overdentures on 2 implants: initial retention values

PURPOSE: This in vitro study aimed to investigate the influence of (1) the interimplant distance and (2) the type of attachment on the retention of mandibular overdentures on 2 implants. MATERIALS AND METHODS: Three stone casts were fabricated, each with 2 implant analogues embedded at distances of 19, 23, and 29 mm apart. Three different interchangeable mandibular overdenture attachments were secured onto the analogues: Hader bars, ball abutments, and stainless steel keepers for new generation neodymium-iron-boron magnets. In total, 45 groups of paired attachments were tested for initial vertical peak tensile load at the 3 interimplant distances. RESULTS: Interimplant (interclip) distance played a significant role only in the retention produced by the Hader bar/red clip configuration. At 19 and 23 mm, the ball/socket attachments were statistically more retentive than the yellow clips, white clips, and magnets, but not compared to the red clips. At 29 mm, the ball abutments showed statistical superiority compared with all other attachments. Mean clinical intercanine distance for conventional full dentures was 22.88 mm. CONCLUSION: Interimplant distance can affect the initial retention of mandibular overdentures on 2 implants depending on the type of attachment used. For a predetermined interimplant distance, attachment performance varies greatly.     

Prosthetic restoration following maxillary trauma utilising a fixed removable implant-supported prosthesis: a case report.

Patients with traumatic head injuries may suffer from tooth loss, as well as involvement of associated soft tissues and bone. Conventional prostheses are often bulky and unretentive. Osseo-integrated implants have made it possible to treat these patients with more retentive, aesthetically and functionally improved prostheses. This case illustrates the use of a fixed removable implant-supported prosthesis for a patient with severe maxillary trauma. A bar connecting the implants was individually designed to have parallel sides and vertical channels prepared in it. The corresponding removable prosthesis features retentive pins which engage the prepared grooves in the bar to provide adequate frictional retention and stability for the prosthesis. This treatment modality restored the missing teeth, alveolar bone, soft tissues and oral function while at the same time facilitating good oral hygiene.     

Adding Retentive Features in the Rebonding of Cast Metal Resin-Bonded Prostheses

Many methods have been used to improve retention in resin-retained fixed prostheses, such as electrolytic etching of the retainer, the labial wrap design, proximal grooves, cast pin retention, and the use of improved adhesive resins such as Panavia EX (Kuraray Co, Osaka, Japan). Insufficient retentive features often lead to debonding of resin-retained fixed prostheses. Debonded prostheses may occasionally be recemented and successfully retained by the addition of retentive features to the prosthesis and abutment teeth. When recementing a debonded prosthesis with questionable retention, additional retention may be added to the retentive wings of the prosthesis by using a Rochette retentive hole in combination with pin retention or enamel/dentinal slots in the abutment teeth.     

Rehabilitation of a missing ear with an implant retained auricular prosthesis

Burns can leave a patient with a severely debilitating disability even after treatment. The objectives of burn rehabilitation are to minimize the adverse effects caused by the injury while rehabilitating the patient''s physical and psychological well-being, maximizing social integration. Long-term success of maxillofacial prostheses mainly depends on the retention. Extra oral implant retained prostheses have proved to be a predictable treatment option for maxillofacial rehabilitation. Replacement of a severely deformed external ear with burned tissues may be satisfactorily accomplished by a cosmetic prosthesis anchored by implants integrated in the skull. The use of such implants is now a well-recognized method for creating a stable result in maxillofacial rehabilitation. This case report describes a safe, simple and economical method for the rehabilitation of a patient with missing right auricle using an implant supported silicone prosthesis. The implant was placed in the mastoid region of the temporal bone. Reconstruction of the ear was done with auricular silicone prosthesis, retained using magnets incorporated in an autopolymerizing resin shim to decrease the weight of the prosthesis on a single implant. This method eliminates the need of tedious laboratory procedures and exact casting and fitting requirements of a metal substructure while minimizing the overall weight and cost of the prosthesis while maintaining adequate support, esthetics and retention of the prosthesis.     

Cleansability of and patients' satisfaction with implant-retained overdentures: a retrospective comparison of two attachment methods

BACKGROUND: Two important factors in the use of implant-retained overdentures are cleansability and patients' satisfaction. Limited research has been published concerning the cleansability of these overdentures On the other hand, studies have compared patients' satisfaction with conventional dentures and various designs of implant overdentures. However, no studies have compared overdentures retained by Hader bars (Sterngold, Attleboro, Mass.) and direct ERA attachments (Sterngold) in terms of both cleansability and patients' satisfaction. PURPOSE: The authors' aim was to determine the cleansability of and patients' acceptance of overdentures retained by direct ERA attachments and overdentures supported by a Hader bar with distal ERA attachments and a Hader clip. MATERIALS AND METHODS: Two groups of 10 subjects each were evaluated: Group A, consisting of patients with overdentures retained by direct ERA attachments, and Group B, consisting of patients with overdentures retained by Hader bars. The authors evaluated the subjects between 18 and 24 months after the delivery of the overdentures by means of a questionnaire and a clinical examination to score each patient on gingival, plaque and calculus indexes. RESULTS: Group A exhibited better results than Group B on calculus, plaque and gingival indexes, but the difference was not statistically significant. The authors found no significant difference between the two experimental groups in satisfaction. CONCLUSIONS: When evaluated in terms of subjects' satisfaction and calculus, plaque and gingival index scores, implant-retained overdentures supported by direct ERA attachments were similar to those supported by a Hader bar. CLINICAL IMPLICATIONS: The two types of overdentures studied are equally satisfactory and easy to clean. Other factors such as biomechanics, patients' preference and previous experience may be more critical when selecting the retention design for an overdenture supported by four implants.     

种植体-杆卡式附着体固位的覆盖全口义齿

目的：总结和评价种植体一杆卡式附着体在覆盖全口义齿中的应用经验和效果。方法：将种植体与杆式附着体结合,以粘膜支持式、混合支持式和种植体支持式３种设计形式,为４６例患者制作种植式全口覆盖义齿,并检查义齿的固位力和稳定性;同时采用修复体测力仪对其中１５例患者义齿的固位效果进行定量评价。结果：３种设计均可达到良好的固位效果,其中混合支持式和种植体支持式的稳定、支持效果更好;应用２￣３只尼龙卡可分别为覆盖     

Stress transfer of four mandibular implant overdenture cantilever designs

STATEMENT OF PROBLEM: The influence of implant number and cantilever design on stress distribution on bone has not been sufficiently assessed for the mandibular overdenture. PURPOSE: The purpose of this simulation study was to measure, photoelastically, the biologic behavior of 2 or 3 implants retaining different designs of cantilevered bar mandibular overdentures and to compare load characteristics. MATERIALS AND METHODS: Two photoelastic models of a human edentulous mandible were fabricated having 2 or 3 screw-type implants (Nobel Biocare, 3.75 x 10mm) embedded in the parasymphyseal area. Bar frameworks using a 7-mm cantilever were fabricated for both models. A clip-retained and a plunger-retained (SwissLoc) prosthesis were fabricated as superstructures for each framework. Vertical loads of 15 and 30 pounds were applied unilaterally to the first molar and 15 pounds to the first premolar on each of the 4 standardized overdenture prostheses. The cantilever was removed from the 2-implant framework and the clip-retained prosthesis was loaded similarly on the first molar with 25 pounds. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. RESULTS: While all 4 prostheses demonstrated low stress transfer to the implants, the plunger-retained prosthesis caused more uniform stress distribution to the ipsilateral terminal abutment compared to the clip-retained prosthesis and provided retention security under tested loads. The plunger-retained prosthesis retained by 2 implants provided better load sharing from the ipsilateral edentulous ridge than the clip-retained prosthesis retained by 3 implants, and lower resultant stresses were seen on the implants. CONCLUSIONS: Under load, all prosthetic designs demonstrated a low stress transfer to the ipsilateral abutment and to the contralateral side of the arch. The plunger-retained prosthesis retained by 2 implants demonstrated a more uniform stress transfer to the ipsilateral terminal abutment than the clip-retained prosthesis retained by 3 implants and provided more retention, given the implant configuration, prosthetic design and arch form.     

Magnet-retained facial prosthesis combined with an implant-supported edentulous maxillary obturator: a case report

The prosthetic rehabilitation of maxillofacial defects is especially challenging when the patient is edentulous. Although dental implants are used to enhance the retention and stability of both facial and maxillary prostheses, combining facial and maxillary prostheses is extremely difficult. This article describes the prosthetic treatment of an edentulous patient with a large maxillary and facial defect. After placing dental implants in the remaining maxilla, a maxillary obturator prosthesis supported by a milled bar attachment was fabricated. The facial prosthesis was retained by a magnetic attachment to the maxillary obturator prosthesis. As the obturator prosthesis was supported securely by this sturdy attachment, the facial prosthesis was stable during mastication and facial movement. The patient reported improvement in prosthesis retention and stability. Both the masticatory and the speech functions of the patient improved.     

Retention Characteristics of Attachment Systems for Implant Overdentures

PURPOSE: The aim of this study was to compare the retention characteristics of various overdenture attachment systems commonly used to retain overdentures to dental implants. MATERIALS AND METHODS: An edentulous mandibular model was constructed incorporating 2 parallel 4.0 mm x 13 mm Branemark implants placed in the canine regions. Attachments were embedded in a metal-reinforced experimental overdenture designed to be dislodged from the model by a universal testing machine. Tensile dislodging force was applied to the overdenture at a cross-head speed of 50 mm/min. Five overdentures were constructed for each of the attachment systems. The attachments evaluated were the Hader bar & metal clip, Locator LR pink, Locator LR white, Spheroflex ball, Shiner magnet, Maxi magnet, Magnedisc magnet, ERA white, and ERA gray. Each apparatus was tested with 5 specimens per attachment system. Peak load-to-dislodgement was measured. Analysis of variance and Scheffe multiple comparison tests were applied to the data with alpha< or = 0.05 level of significance. RESULTS: Peak load-to-dislodgement for all attachment systems ranged from 3.68 +/- 1.32 N to 35.24 +/- 1.99 N. Strain-at-dislodgement, calculated from stress-strain curves, ranged from 0.78 +/- 0.20% to 2.78 +/- 0.5%. The ERA gray attachment demonstrated the greatest retention, with a peak load-to-dislodgement of 35.24 +/- 1.99 N, and a relatively low strain-at-dislodgement of 1.64 +/- 0.09%. Less retention was recorded for the Locator LR white, Spheroflex ball, Hader bar & metal clip, and ERA white systems. The Locator LR pink attachment demonstrated still less retention with a load-to-dislodgement of 12.33 +/- 1.28 N. Significantly high strain-at-dislodgement was recorded for the Hader bar & metal clip and Locator nylon attachment systems. The lowest dislodging loads and strains were recorded for the Shiner magnet, Maxi magnet, and Magnedisc magnet attachments. CONCLUSIONS: Results suggest that the attachment systems evaluated may be grouped into high (ERA gray), medium (Locator LR white, Spheroflex ball, Hader bar & metal clip, ERA white), low (Locator LR pink), and very low (Shiner magnet, Maxi magnet, Magnedisc magnet) retention characteristics.     

Alternative retention for an implant-retained auricular prosthesis

The introduction of intraoral endosseous implants was inevitably followed by their external use in maxillofacial prosthodontics. Bar and clip attachments provide satisfactory retention for auricular prostheses, although the bar may inhibit patient hygiene by limiting access to the defect area. A simple clinical and laboratory technique to enhance the retention of an implant-retained auricular prosthesis is described, with custom-made stud attachments used for retention. Improved access for hygiene is provided. A clinical case is presented.     

Magnet-retained auricular prosthesis with an implant-supported composite bar: a clinical report

The use of craniofacial implants to assist in retaining auricular prostheses often requires complex laboratory procedures, involving production of an accurate casting, fitting of a precious alloy bar, and the use of clips. A simplified method for the retention of an auricular prosthesis with a composite bar and magnets is described in this article.     

Nonimplant,Nonadhesive Overlay Approach to Retain a Partial Auricular Prosthesis

Partial auricular prosthesis fabrication presents a more complex challenge than complete ear fabrication, with added aspects of merging/camouflaging a larger prosthetic marginal area, pattern try‐in, and compromised retention. Better alternatives are excision of the remnant ear to make an implant‐retained complete ear prosthesis or surgical reconstruction of the missing ear portion. Both need additional surgery/ies and expenses, neither of which may be acceptable to the patient. This report describes a prosthesis fabrication approach for such patients. This approach does not require implants or adhesives for retention. Issues of marginal camouflage and pattern trial were also addressed satisfactorily.     

Tissue-supported implant overdentures.

Overdenture techniques can be modified for use with implants. Generally the implants, which replace the tooth roots, can be placed in a position to permit optimum retention and stability as well as enhancing esthetics. Bony undercuts, which at times are present with the retention of tooth roots, are not a problem when using implants. Various retentive schemes are available to retain the prosthesis and can be matched to the individual needs of patients in regard to retention, stability, and the ability to insert and remove prostheses. Two implants can adequately support an overdenture. The superstructure must be designed to enable the patient to maintain a healthy oral environment. The patient must understand and be able to perform required oral hygiene procedures. The use of overdentures over implants affords the dentist another option in meeting the needs of the patients.     

A Novel Method for Retention of an Orbital Prosthesis in a Case with Continuous Maxillary and Orbital Defect

Exenteration of the orbital contents as well as removal of a part of maxilla with an ablative surgery for the removal of a malignant tumor can severely affect a person in terms of function, esthetics and psychological trauma. A well-retained, user-friendly, removable maxillofacial prosthesis is the key to successful prosthetic rehabilitation in such cases. Various retentive techniques include using spectacle frame, conformers, adhesives, osseointegrated implants, magnets or buttons. This paper describes a novel technique for retention of silicone orbital prosthesis using acrylic resin base attached to maxillary obturator with the help of pin and socket of an electric plug wherein the latter is attached to the eye prosthesis with the help of a mechanical undercut. This helps in better retention of both the prostheses.     

Photoelastic analysis of implant-retained and conventional obturator prostheses with different attachment systems and soft relining

Complete and partial loss of maxillary bone may jeopardize oral physiology and generate complications as oral-sinus-nasal communication. Palatal obturator prostheses are a treatment alternative for rehabilitation of these patients. The aim of this study was to assess stress distribution, through photoelasticity, on palatal obturator prostheses associated with different attachment systems (o'ring, bar clip, and o'ring/bar clip) of implants and submitted to relining. Two photoelastic models were fabricated according to an experimental maxillary model with oral-sinus-nasal communication. One model did not present implants, whereas the other included 2 implants with 13.0 mm in length in the left ridge. Four colorless maxillary obturator prostheses were fabricated and relined with soft silicone. One of these prostheses presented no attachment system, whereas the remaining prostheses included attachment systems adapted to the implants. The assembly (model/attachment system/prosthesis) was positioned in a circular polariscope during loading with 100 N at 10 mm/s. The results were based on observation during the experiment and photographic records of stress on the photoelastic model. The bar clip system exhibited the highest stress concentration followed by o'ring/bar clip and o'ring systems. The attachment systems presented different stress distribution with greater concentration surrounding the implants and homogenous stress distribution on the photoelastic model without implants. The highest concentration of fringes occurred, in ascending order, with o'ring, o'ring/bar clip, and bar clip systems.