Fixed Theoretical Fall 2024 PDF

Terminology And Classification of Crowns and Bridges Dentistry is the health science that encompasses the study and application of measures designed to prevent deterioration of the oral structures and the use of pertinent clinica...

Terminology And Classification of Crowns and Bridges Dentistry is the health science that encompasses the study and application of measures designed to prevent deterioration of the oral structures and the use of pertinent clinical procedures to improve the oral health of those treated. Among its many ramifications are the relief of pain, the treatment of oral disease, the maintenance of masticatory efficiency, and the maintenance of or restoration of the esthetic qualities of the mouth and face. Definition of terms Prosthesis: is any artificial replacement of a missing body part. PROSTHODONTICS: it is the that branch of dentistry pertaining to the restoration and maintenance of the oral function, comfort, appearance and health of the patient by the restoration of the natural teeth or replacement of missing teeth and oral and maxillo-facial tissues with artificial substitutes, or by both. Prosthodontics is either removable prosthodontics or fixed prosthodontics. Removable prosthodontics: is that branch of prosthodontics concerned with the replacement of teeth and contiguous structures for edentulous of 1  partially edentulous patients by artificial substitutes that are removable from the mouth. Fixed prosthodontics: is that branch of prosthodontics concerned with the restoration or replacement of teeth or both by artificial substitutes that are not removable from the mouth. I- CROWN: It is an artificial replacement that restores missing tooth structure by surrounding most or all of the remaining structure with a material such as cast metal, porcelain, or combination of materials such as metal and porcelain. It is intended to reproduce both the form and the function of the tooth and, some instances, to restore or enhance the appearance. Extra coronal restoration I. Full veneer crown: It is an extracoronal restoration that involves all of the surfaces of the clinical crown. The restoration material ma be all metal full veneer metal crown all porcelain ceramic porcelain jacket crown or a metal-ceramic combination “veneered and full veneered crown” ( fig.1). II. Partial veneer crown: It is an extracoronal restoration that restores only a portion of the clinical crown (fig.2). 2  Fig. 1: Full veneer crown Fig. 2: partial veneer crown Three Quarter Crown It is a partial coverage, cast crown restores the occlusal surfaces and all the axial surfaces except the facial surface retained in position by grooves prepared on the proximal surfaces (fig.3). Reversed Three Quarter Crown Modified ¾ crown in which the buccal surface is prepared instead of the lingual surface. One Half Crown It is partial coverage cast crown, which involves mesial surface and the mesial halves of the buccal and lingual surfaces and half of the occlusal surface. It is retained in position by buccal and lingual grooves (fig.4). 3  Seven-eight Crown It is extension of the three-quarter crown to include a major portion of the facial surfaces, usually the disto-buccal cusp. It is retained in position by buccal and mesial grooves (fig.5 A and B). MacBoyle Retainer Is a modified three-quarter crown, with its retention derived from two grooves at the labio-proximal line angles. It is indicated for mandibular anterior teeth. Pin-ledge Retainer It is a partial coverage restoration retained by two ledges and three pins, two incisally and one gingivally (fig. 6). Temporary Crown It is a crown made and used temporarily for the protection of the prepared tooth until the crown is completed and ready for cementation. Fig.3: Preparation for three-quarter crown Fig.4: Preparation for one-half crown 4  (A) (B) Fig. 5(A and B): preparation for seven-eight crown (A) (B) Fig 6 (A and B): Pinledge retainer 5 Intracoronal Restorations Inlay Retainer: It is an intracoronal cast restoration, restoring the proximal and occlusal surface of the tooth but does not protect or cover the cusp (fig. 7). It is used to support the occlusal rest in fixed-supported bridge. Onlay retainer: It is a modification of the inlay with cusp overlay on the occlusal surface to protect the integrity of the remaining tooth structures (fig.8). Fig.7: MOD inlay Fig.8: MOD onlay 6 Intraradicular Restoration Radicular retained restorations consist of a post or dowel with an attached core that obtains its retention and resistance to displacement from post inserted in the prepared root portion of an endodontically treated tooth (fig.9). While the root preparation retains the post, the core establishes retention for a complete veneer crown. This post and core may be custom cast (the radicular retainer is fabricated to fit the root preparation) or prefabricated (the root preparation is designed to fit a stock post and a core is built up with amalgam, composite resin, or modified glass ionomer cement). Fig. (9): Dowel-core 7