STRESS BREAKER OR STRESS EQUALIZATION

SEMINAR ON STRESS BREAKER OR STRESS EQUALIZATION : SEMINAR ON STRESS BREAKER OR STRESS EQUALIZATION PRESENTED BY :- DR. IPSHA DHALI

Slide 2 : There are 4 basic underlying approaches to distributing the forces acting on a partial denture, between the soft tissue and the teeth. Conventional rigid design Stress equalization or stress breakers Physiologic basing Broad stress distribution

Stress equalization or stress breakers : Stress equalization or stress breakers Dentures with a stress breakers are also called as broken stress partial dentures or articulated prostheses.

Definition :- : Definition :- A stress breaker is a device which relives the abutment teeth of all part of the occlusal forces. A stress director is a device that allows movement between the direct retainer which may be intracoronal or extracoronal. or

Introduction :- : Introduction :- Emphasizes that the resiliency of the tooth secured by the periodontal ligament in an apical direction is not comparable to the greater resiliency and displace ability of the mucosa covering the edentulous ridge. Due to this, forces are transmitted to the abutment teeth as the denture bases are displaced in function. Stress breaker can be added to the junction between the tooth supported portion and tissues supported portion of the denture to avoid leverage forces

Introduction :- : Introduction :- It is the belief that a rigid connection between the denture bases and the direct retainer on the abutment tooth is damaging and that some type of stress director or stress equalizer (a flexible or movable joint between teeth and metal frame work so that the base can move independently of the clasp) is essential to protect the vulnerable abutment teeth.

There are two types of stress breakers :- : There are two types of stress breakers :- Type I Type II

Slide 8 :

TYPE I :- : TYPE I :- Here a movable joint is placed between the direct retainer and the denture base. This joint may be a hinge or a ball and socket or a sleeve and cylinder. Adding all these allows the denture base to move independently. This decreases the amount of force acting on the abutment. Combined resiliency of the periodontal ligament and the stress director will be equal to the resiliency of the oral mucosa overlying the ridge.

Slide 10 : Examples :- DALBO, CRISMANI, ASC52 attachments. The denture base shows independent movement with type I stress breakers

TYPE II : TYPE II It is a flexible connection between the direct retainer and the denture base. It can be a wrought wire connector, divided or split major connector or a movable joint between two major connectors. In a split major connectors the major connector is split by an incomplete cut parallel to the occlusal surface of the teeth into two units namely the upper unit and the lower unit.

Slide 12 : The denture base is connected to the lower unit and the rest and the direct retainers are connected to the upper unit. Split major connector or type II stress breaker

Advantages:- : Advantages:- This design usually calls for minimum direct retention because the denture base operates more independently than a conventional denture. Internal attachments for retention of a stress broken prosthesis are widely used. The stress director eliminates the tipping on the tooth, thus preventing bone resorption about the tooth. Intermittent pressure against the mucosa caused by the movement of the denture base has a massaging effect on the underlying bone and soft tissue. It minimizes tissue change and reduces the necessity of relining and rebasing the denture to compensate for tissue changes as is required for most distal extension partial dentures. Weak abutment teeth are well splinted even during the movement of the denture base.

Disadvantages : Disadvantages The stress director is fragile. Reduce stability against horizontal forces. Reduce indirect retention. Its lack of ability to prevent damaging lateral stresses from occurring on the edentulous ridge can result in rapid resorption of bone and settling of the denture. If sufficient thickness of metal is used in the hinge to prevent lateral movement, the prosthesis becomes heavy, bulky and annoying to the patient. Its construction is complex and costly. It requires constant maintenance and may be difficult or impossible to repair. Assembly is very weak and tends to fracture easily. Distorts to rough handling. Both vertical and horizontal forces are concentrated on the ridge leading to resorption. Split major connector tends to collect food debris at the area of split.

Slide 15 : THANKYOU