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"O"-ring attachment in removable dentures
Abstract Objective: To increase the removable dentures, buffer stress. : Similar to the telescopic denture design, the inner crown connected to the fixed base tooth bond, the outer crown and denture stent placed in between the "O"-ring, so that the organic integration. Cut into 1/3 design an annular groove in the inner crown axial plane; the medial wall of the outer crown design a groove between the two grooves put the "O"-type silicone rubber ring. Results: The "O"-ring denture retention is good, and to protect the abutments adapt to levy wide, to facilitate production. Conclusion: "O"-ring denture is a good removable partial denture design.
"O"-ring attachment sleeve crown removable partial denture
"O"-ring attachment removable partial denture telescopic crown removable denture base improved method, similar to the telescopic crown removable denture abutments, the outer layer of the highest increase between the "O" type silicone rubber ring to increase retention [1,2]. Baum, in the 1980s  proposed the "O" ring dentures improve through the "O"-ring elastic retention force between the inside and outside the crown retention effect, but also facilitate the production of clinical applications and laboratory, an increase the breadth. Baum himself under the guidance of five years, our department carried out the repair, and achieved satisfactory results.
"O"-ring attachment removable partial denture is a deep cut in the shaft surface of the inner crown of the abutment teeth 1/3 of design about 0.5 to 0.75 mm, 1 mm wide ring groove, while the corresponding location in the outer crown The side also designed a groove, and a "O"-type silicone rubber ring placed between the two grooves, use it to generate the exercise of the dual retention force of friction between the elastic retention and double sleeve.
Materials and Methods
Materials: 1. "O"-ring, a special kind of silicone ring (provided by Dr.Baum Dental Centre). (2) Metal: crown available fusion in a gold alloy or gold, foreign crown alloy design choices based on the crown surface, ceramic alloy or stent alloy.
Second, the clinical course: 1. Denture design and abutments options: "O"-ring attachment removable dentures can be divided into (a) full-arch denture; (b) the hybrid denture. (2) to take the research mode: take the research model, the model viewer to establish a common place of the bracket Road. Abutment preparation: the abutments buccal surface must be uniform to wear in addition to 2 to 2.5 mm, and the elimination of the undercut, and then cut () 1/3 even rubbed off 0.5 mm, to give the groove of the inner crown enough space. (4) test the inner crown: laboratory production, polishing a good inner crown on the abutment teeth to try them, requires a normal edge and bite, the inner crown grooves must be depth of 0.5 to 0.75 mm wide 1 mm, wall straight to the bottom level. Then bonded to the inner crown with zinc-phosphate cement abutments (see Figure 1). Select an appropriate size of type "O" ring into the groove of the inner crown (see Figure 2), modulus, and the anhydrite down model, Silastic whole jaw records. Send laboratory to produce the outer layer of the crown and bracket. Test the outer layer of the crown and the stent: the outer layer of the crown must be consistent with the inner crown, and "O"-ring is fully seated (see Figure 3,4), available Fit,-Check to check both whether the groove is consistent . Take embankment record, sent to the laboratory to complete the restoration. Wear teeth: the outer layer of the crown restorations wear tune into the disease population, try them on, put the "O"-ring, multiple abutments can be the first to put an "O" ring, after retention increase the number of "O" ring.
Figure 1 abutment tried on the inner crown
2 "O"-ring into the crown groove
Figure 3 outer crown profile
Figure 4, the outer layer of the crown, consistent with type "O" ring in place
10 "O"-ring attachment dentures of application of this design produced eight patients, including three full-arch "O"-ring attachment dentures, 7 for the "O"-ring attachment and clasp stent and retention. Design "O"-ring attachment abutments 21, of which 6 have mild loose teeth, root canal treatment and root 8, severe wear of teeth and misplaced teeth one each. After five years of application, the addition to the case of full-arch denture plastic fracture due to the surface of roast, and the remaining effects are good. X-ray examination six loose base periodontal were not found to have significant periodontal absorption increase. And root did not occur to break the eight root canal treatment. Eight patients with a sense of denture comfort and chewing powerful.
"O" ring attachment activities the dentures unique in that:
With telescopic crown compared to the telescopic crown retention is mainly relying on the friction force between the inner crown and outer crown, which increases the difficulty of laboratory production; at the same time as well as to the choice of the multi-abutment axis parallel to the surface between the abutment, "O"-ring attachment not only use the friction force as retention and by "O"-ring to the inner crown and outer crown organic combination of and adds an elastic solid force to support the friction between the outer crown. So that you do not need a parallel between the axial plane of the abutment teeth so to create a simple choice of abutments.
2. "O"-ring will not only increase through its stretching elastic between the inner crown and outer crown retention, and can buffer stress, the stress distribution, thus protecting the abutments; in the preparation of the abutments, in accordance with the base reduce the height of the abutment to the special circumstances of teeth, change the proportion of crown and root; tends axial hydraulic conductivity and abutments, to reduce the increase in torque on the abutment teeth, the lateral force, the rotational force to better protect the base teeth. "O"-ring denture abutments splints role, increase abutment stability and resistance to lateral forces [1,2]. Berg,  that the attachment can play the role of dispersion of force.
In the choice of abutments, it has a wide range of indications, to solve the anterior teeth as abutments exposed metal, mild loosening of teeth, elongation of teeth, tooth dislocation, reverse the teeth, severe wear of tooth after root canal treatment residual root and crown as an abutment . The same applies to the implant.
(4) in the production, it does not require sophisticated equipment, the number of teeth as abutments to establish a common place Road without affecting retention.
Denture production of "O"-ring to facilitate a wide range of indications, relatively low-cost, than sleeve denture retention and more favorable, and the abutment teeth, etc., "O"-ring denture is a good Abstract - fixed design. Baum and other decades, the clinical proof of this, the department four years of clinical type "O" ring denture is a removable partial denture design a good
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