Dr. Prajna P Shetty / Dr Ramesh Chowdhary
This article has been published in journal of contemporary practice in 2016.{ The Journal of Contemporary Dental Practice, September 2016;17(9):780-782}
Type of article: – Case Report
TITLE OF THE ARTLCLE:- Hidden over denture bar in fixed implant retained hybrid prosthesis-
RUNNING TITLE:-case report of a Novel technique.
ALL CLINICAL CASES
Introduction
Every patient needs a comprehensive treatment planning. Dentists must consider the advantages and disadvantages of the available implant prosthetic options and match them to patient’s expectations.(1) A hybrid denture prosthesis is one that is fabricated and retained by screw threaded into implant abutments, most of the time on 4 implants.(2) A passive-fitting substructure for fixed removable screw retained hybrid prosthesis is arguably one of the most technically intricate tasks in implant dentistry. The rehabilitation of edentulous patients with hybrid dentures has been observed to achieve greater masticatory function and psychological satisfaction than with conventional over-dentures.(2) It can be a fixed-fixed type or a fixed removable type of prosthesis. Each of them has a varied amount of advantages and their own shortcomings. Some times due to failure of a implant, the prosthesis needs to be replaced with a newer castings to accommodate the existing implants. To harness the advantages of both types, a novel way of fabrication of the prosthesis is been explained.
Clinical consideration: This article presents a novel technique, wherein the existing framework of the fixed prosthesis can be used to convert the fixed prosthesis to removable prosthesis on the existing implants, without recasting.
Clinical significance: The implant is economical and easily convertible from a fixed-fixed to a fixed-removable prosthesis. Hence, there is reduced morbidity, reduced cost, and an increased psychological comfort for the patient.
Keywords: Dental implants, Hidden bar, Hybrid prosthesis, Overdenture.
Case report
A 40 year female presented to our department with completely edentulous maxillary and mandibular arch. An all-on-four implant supported hybrid prosthesis was planned for both the arches and was conveyed to the patient. After the consent from the patient, surgical placement of 4 implants in maxilla and four in mandible was carried according to the conventional protocols (Fig 1).
At the time of three months of follow up , if was found that one of the maxillary implant was mobile and was required to be retrieved(Fig 2). After retrieval of the failed implant, patient was not willing for any further implant placements. Hence it was decided to go ahead with the existing three implants in maxilla and four implants in the mandible. Due to the financial constrains of the patient, it was decided that, the prosthesis has to be made, such that, even after any additonal implant failure in future, the prosthesis can be converted and can be used as bar retained over denture, without re-doing the framework.
Technique-
- UCLA non-hex abutments were used, the custom abutments were milled and checked for parallelism with a surveyor, and these milled abutments were connected to each other with a coffee straw with the help of inlay wax.(3) The coffee straw mimicked the Hader bar in size and dimension accurately (Fig 3).(3)
- wax pattern was invested and casted into a nickel chromium bar framework. The framework was checked for the fit in the mouth, which was confirmed with a orthopento radiogaph (OPG). Special care was taken to see that the hader bar design of the bar is maintained (Fig 4).
- The bar was envoloped in the modelling wax and jaw relation recording was carried out in the patient mouth followed with teeth arrangement. Once the try-in was satisfactory esthetically and functionally, heat cure polymerisation was carried out in the routine procedure.
- The cured hybrid prosthesis was finished and polished, and access vents were made in the place of abutment screws in the hybrid prosthesis. After occlusal corrections and patients concent, the prepared prosthesis was tightened in the patient mouth, followed by a confirmatory radiograph to check for the final fit of the prosthesis (Fig 5).
- A 2-year periodic follow-up showed no bone loss or any other untoward failures or problems, which is our ministep toward success.
DISCUSSION
Dental implant retained restorations in edentulous patients can be performed by screw retained acrylic prosthesis, screw retained metal-ceramic prosthesis and cement retained metal ceramic prosthesis.(4) Polymethyl methacrylate (PMMA) denture bases have a very good biological, mechanical and esthetic properties.(4) The hybrid gets its strength from the metal substructure that limits the chances of fracture. Use of screw retained prosthesis is recommended in cases of poor denture retention.(5-7) The rehabilitation of the edentulous patients with hybrid dentures has proven to achieve greater masticatory function, esthetics and psychological satisfaction than conventional overdentures, and it is more affordable with similar results than the full mouth implants.(8, 9)
Bar retained implant hybrid prosthesis is usually customised with a hader bar. In the present technique, plastic coffee straw (stirrer) which mimics the dimension and size of the hader bar was used . The purpose of using a hader bar design, instead of a conventional metal frame for the hybrid prosthesis design was to provide a hidden over denture bar. In case, patient is not maintaining the fixed prosthesis in a good condition, and it is required to maintian the oral hygiene. Thus a removal prosthesis is required at that time and this fixed prosthesis can be converted to a bar retained removable over denture, just by removing the acrylic portion of the prosthesis and providing retentive clip to the newly made overdenture and connecting the attachments to the existing hader bar. The hidden bar concept can also be useful, when an existing implant fails, in a all-on four concept then, then the prosthesis can be converted to a removable overdenture.
Conclusion- This noval concept of hidden over denture bar designed for a hybrid prostheis will be very help in easily converting a fixed implant supported restoration to a removable implant supported restoration, without changing the metal framework. Thus, providing a economical approach to the clinicians and patients.
Fig 1. Radiograph showing four implant each placed in maxillary and mandibular edentulous arch
Fig 2. Radiograph showing one implant failed in the maxillary arch from the previous four implant placed.
Fig 3. Wax pattern framework of the coffee stick bar connected on to UCLA abutments mounted on the cast.
Fig 4. Casted header bar connected to on dental implants.
Fig 5 . Radiographic image showing coffee stick bar fitted on the implants intra orally.
Fig 6. Hybrid prosthesis in situ made on the coffee bar frame work
References
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