Indications I. Tooth born partial denture (removable bridge). II. On free-end extensions where undercut is so small that longer clasp arms will not be retentive.
Use on isolated lower molar with undercut located meso-lingually due to lingually tilted tooth.
Back Action Clasp
I. Premolar and canine abutments on free-end extension . II. On short teeth with small mesiofacial and distal undercut.
Not used on molars because of length of clasp arm.
Premolar abutment with lingual inclination on free-end extension partial denture.
I. Maxillary partial denture for esthetic reasons. II. When there is a severe softtissue undercut inferior to marginal gingiva
(modification of ring clasp)
Reverse Back Action Clasps (joining of a bar & back action clasps with all their disadvantages)
Half & Half Clasp "Split Clasp"
I. Premolar and molar abutment for free-end extension P.D. and removable bridges . II. Isolated teeth.
Advantages I. Good support and bracing . II. Simple design . III. Dose not distort easily . IV. Easy to adjust . V. Contacts minimal area of the tooth . VI. Good esthetics.
Disadvantages May traumatize abutments when used incorrectly on free-end extension.
It covers large area of the tooth making it unaesthetic, so it used only in posterior teeth. I. Can use small undercut I. Easily distorted because of areas length. II. Length of clasp II. Difficult to adjust. produces resiliency and III. Large tooth area covered. "stress-breaking" effect on IV. Design produces "food abutments for free-end trap" between lingual arm extension partial denture. and major connector. Has "stress-breaking" I. Crosses soft tissue. action similar to "back II. Excessively long clasp, action clasp". easily distorted, difficult to adjust. III. Poor esthetics. IV. Contacts large areas of tooth. I. Good support and Food trap may be introduced bracing . between lingual arm and II. Easy to adjust . major connector if not III. Contacts minimal area constructed properly. of the tooth . IV. Good esthetics.
Type Clasp Reverse Action Clasp (Hairpin, CClasp, & Fishhook)
Embrasure Clasp (Butterfly Clasp or Double Akers' Clasp)
T – Clasp I – Clasp U -Y– Clasp L – Clasp R – Clasp
Indications I. When a proximal undercut must be used to a posterior teeth and high tissue undercut prevents the use of a bar clasp. II. Distofacial undercut on canines and premolars when a sharp tissue undercut prevent use of bar-type clasp. III. Undercut near minor connector on molars. I. To utilize multiple abutments and distribute occlusal support and retention to several teeth . II. When insufficient undercuts are present on a single abutment . III. Specially used for the purpose of a bilateral bracing in a unilateral edentulous arch, to utilize a retentive undercut. Two opposing circumferential clasps joined at the terminal end of the two reciprocal arms, used when multiple clasping is needed. On maxillary lateral incisors which are abutments for a removable bridge (tooth born partial denture) or tooth borne side of a unilateral free-end extension. I. Small shallow undercut present in the cervical ⅓ of anterior teeth. II. Approaches the undercut is an inconspicuous (hidden) way; serve esthetically.
Contraindications On maxillary teeth where the metal is objectionable.
I. Not to be used where clasp would traumatize abutment teeth. II. Cannot be used where there is insufficient space for the minor connector to cross the occlusal surface.
Advantages I. Undercut adjacent to edentulous area may be utilized without having minor connector cross soft tissue . II. Good bracing and support . III. May be used on freeend extension P.D. or removable bridges. I. Good support and bracing. II. Distributes support, bracing and retention to several teeth.
I. Good esthetic. II. Good support and bracing.
Disadvantages I. Poor esthetics . II. Large area of the tooth surface is covered . III. Possible food trap.
I. Minor connector usually too thin on occlusal surface resulting in excessive breakage. II. Retention may be excessive.
Tooth must be prepared by dentist so that proximal surfaces of the tooth are parallel or have slight convergence incisally.