What is a bar prosthesis?
A bar prosthesis is a combined dental prosthesis. The restoration consists of an element firmly anchored in the jaw - either surgically fixed implants or at least two remaining natural teeth - and a removable component. Both parts are connected by a bar, and thus firmly implemented in the jaw. Implants or remaining teeth and bar form the primary fixed framework in the jaw. The classic bar concept includes four implants to provide broad support and strong retention and to prevent the prosthesis from tilting. The bar framework locks the implants together and ensures that they remain immobile and stable even when immediately loaded after placement. The removable denture has a bar rider with openings at the base, which slides precisely onto the bar. Optionally, this is supported by additional, easily exchangeable retention elements such as Preci-Vertix matrices or locators screwed onto the bar. Bar prostheses are used for both mandibular and maxillary restorations and are available as partial dentures or implant-supported full dentures.
Side fact
The success story of implants began with the bar technique by the Swedish orthopedist and researcher Per-Ingvar Brånemark in the 1960s. For a long time, bars were considered the only safe technique for restoring edentulous patients with dental implants. Incidentally, a bar restoration should not be confused with an All-on-4 prosthesis, which comprises four implants and a fixed, non-removable prosthesis built on top of them.
When is the bar prosthesis used?
A bar prosthesis is ideal if patients only want to afford four implants, prefer a removable solution and want a final and fully loadable denture with a long service life as well as optimum esthetics and chewing ability. The bar prosthesis is recommended if no sinus lift with insertion of suitable bone replacement and long-term healing is possible or desired in the dorsal maxillary region and the remaining teeth are very reduced or severely affected. By splinting the implants per bar, no further bone resorption due to overloading takes place.
The fabrication of a bar denture
Whether as a partial or full denture, a bar prosthesis offers a reliable permanent dental solution that combines the advantages of fixed bridges and removable restorations.
Manufacturing options: prefabricated versus customized
There are two alternatives here: a prefabricated bar or a customized bar. The fabricated bar - for example, a Dolder bar - has a prefabricated profile with integrated bar tabs to accommodate the prosthesis. As a rule, prefabricated also means more cost-effective, but prefabricated bars do not always fit every jaw situation perfectly. Prefabricated bars have significantly higher complications in the area of retention loss than customized bars. A customized bar, on the other hand, is custom-made to fit the jaw and makes maximum use of the usually limited space available for retention areas. Retention is therefore excellent, which conveys safety with the denture in everyday life. Due to the rigid design with a rigid anchorage, the complication rate is reduced.
Manufacturing methods: casting, milling, LaserMelting
In the past, bar prostheses were manufactured by casting. Due to the solidification of cast metal parts and shrinkage of the material volume as a result of cooling, shrinkage cavities and material distortions can occur. Modern manufacturing methods in bar dental technology rely on homogeneous and stress-free digital CAD/CAM milling from the materials CoCr (not precious) or titanium. Bars can also be implemented in LaserMelting - an additive process with the highest filigree and precision, the results of which exhibit a metal structure in the quality of rolled industrial steel. Milling and LaserMelting have specific advantages and disadvantages in the production process and in post-processing. The milled bar requires less post-processing compared to LaserMelting production. On the other hand, production is more cost-efficient with LaserMelting.
Connection of abutment with bar
An implant-based bar prosthesis consists of two parts, the abutment, which is screwed to the implant, and the exactly matching counterpart in the prosthesis. The implant is anchored in the patient's bone, the abutment serves as a link to the bar prosthesis in the upper and/or lower jaw. The abutment acts like a die and is either bonded to the bar or produced directly together with the bar as a single unit, which provides more stability, as bonding processes are always potential sources of erosion. However, depending on the jaw situation and insertion direction, abutments cannot always be produced as a unit with the bar.
Metal-free alternatives
Bar and implants are usually made of titanium, which is particularly durable and resistant. Restorations made of non-precious metals (CoCr) or gold alloys are also possible. The use of electroplating is also feasible.
Alternatively, metal-free variants with high biocompatibility made of zirconium oxide for the primary bar and of the high-performance polymer PEEK for the secondary bar overlay are available.
Advantages of the bar denture
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Proven, safe method of a removable denture based on implants or as a tooth-guided bar, even in cases of bone loss in the posterior jaw region
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Firm retention of the prosthesis on the bar, functionally like fixed teeth
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Fast, final immediate restoration
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Easy handling for patient
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No palatal plate required in the upper jaw, therefore optimum mouth feeling, no impairment of taste and speech
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No further bone loss due to overloading
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Filigran bar with plenty of space for esthetic restoration
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Possibility of aesthetic compensation in case of severe jaw atrophy by means of gingiva-shaded denture saddles including relining
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Simple and cost-efficient replacement of the retention elements in case of bar deterioration of riders
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A clean solution for periodontal hygiene with good cleaning tolerance
Disadvantages of the bar prosthesis
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Expensive production for dental laboratories due to high material and labor costs
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Expensive for patients (not included in standard health insurance coverage)
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Surgery required for implants
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Possible foreign body feeling, key point: denture feeling
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Difficult to clean the bar, food residues may remain under the prosthesis, professional tooth cleaning recommended
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With metal solutions: abrasion with reduction of fixation, alternative: additional retention elements such as Preci-Vertix matrices or locators screwed onto the bar.