Crowns and Fixed Partial Prosthodontics

General Guidelines
Crowns include the following acceptable restorations: full crowns, seven-eighths crowns, three-quarter crowns, inlays and onlays. They may be made of a metal alloy, ceramic material, acrylic or composite resin, or a combination of these materials. The properties of the chosen materials used must be compatible with that of the opposing dentition.

Crowns are indicated when:

• The restoration will receive excessive masticatory force that might fracture the remaining tooth structure or when a more conservative restoration is contraindicated;

• There is a fractured or missing cusp or incisal edge (a veneer type restoration may also be indicated);

• The majority of the tooth surface is restored but defective;

• There is gross decay on most tooth surfaces;

• The patient has lost significant occlusal vertical dimension with heavily abraded or eroded occlusal surfaces;

• An existing crown demonstrates unacceptable margins, contours, contacts, occlusal anatomy, cosmetics or recurrent caries;

• A tooth is unsightly due to extreme discoloration or malposition (veneer restorations and orthodontics should be considered respectively as well).

A definitive restoration of a tooth that requires endodontic and/or periodontal treatment should be postponed until a favorable prognosis has been established. The crown must be incorporated in the treatment plan in the appropriate sequence in relation to endodontic, periodontal and surgical procedures.

The patient’s age, health and general oral health and the patient’s wishes and attitude must also be considered. Fixed partial prostheses are indicated for replacement of one or more missing teeth when abutment teeth can be expected to have a reasonable prognosis for years of service. The number, location and character of the abutment teeth and number of pontic replacements must be adequate for the intended purpose of the fixed prosthesis. Retainers must adequately cover the abutments, resist dislodgement and join adjacent retainers with satisfactory connectors.

Crowns and fixed partial prostheses are contraindicated when:

• The necessary operative procedures impair the patient’s oral health.

• The operative procedures inhibit growth and development.

• There is no clear rationale for improving or stabilizing present dental function.

Crowns and Fixed Partial Prosthodontics Quality Evaluation Criteria

ITEM	RATING AND EXPLANATION
	ACCEPTABLE	NOT ACCEPTABLE
Treatment Planning	1.        Adequate pretreatment records (radiographs, patient history, diagnostic casts, etc.). 2.        Root structure and supporting soft and hard tissues adequate to support the prosthesis, and no compromising pathology.	1.        Lack of proper pretreatment records. 2.        Inadequate support for the prosthesis in supporting structures, and/or compromising pathology.
Surface and Color	1.        The surface of the restoration is smooth with no irritation of soft tissue. 2.        There is no significant mismatch in color shade or translucency between the restoration and adjacent teeth (anterior teeth only).	1.        Surface is rough, pitted, grossly irregular, very porous or fractured. 2.        There is a noticeable mismatch between restoration and adjacent teeth (anterior teeth only).
Anatomic Form and Occlusion	1.        Restoration contour is in functional harmony with adjacent teeth and soft tissue with good individual anatomic form. 2.        Size, shape and contour esthetically pleasing, consistent with age, sex and complexion. 3.        Harmonious occlusion with no premature contacts and no interferences in excursive movements.	1.        Restoration is over contoured, under contoured, open contacts, marginal overhang, and damage to tooth, soft tissue, or supporting periodontal tissues, marginal ridges of uneven height. 2.        Improper size, shape or contour, not consistent with age, sex, and complexion. 3.        Lack of occlusion, premature contacts—or interference in lateral or protrusive excursions.
Main Integrity	1.        Margins nicely finished and well-adapted to the tooth with no clinical or radiographic evidence of opening, overhang or deficiency. 2.        Margins finished in a cleansable area.	1.        Open, thick, short or overhanging margins, visible clinically or radiographically. 2.        Margins cannot be adequately cleaned.

Removable Partial Prosthodontics
Removable partial prosthodontics deals with the replacement of teeth by means of removable appliances that may be either entirely tooth supported or tooth and soft tissue supported. The appliance usually derives its support principally from tissues underlying its base with a lesser amount of support from the remaining teeth. If a removable appliance is used as an interim prosthesis, it may be entirely tissue borne. If it is supported both mesially and distally by abutment teeth, it may be entirely tooth borne. The prostheses should function passively, fit the natural teeth accurately, be well adapted to the soft tissues and provide adequate masticatory function for the patient.

• A removable partial prosthesis is indicated when:

• One or more teeth are to be replaced and a distal abutment is absent.

• Replacement of an anterior tooth or teeth is required immediately following extraction and an acrylic provisional appliance will provide adequate esthetics during healing.

• A provisional appliance is used where a final diagnosis cannot be made.

• It may serve as a more esthetic alternative for replacement of missing anterior teeth.

• Edentulous spans are too extensive and/or resorbed to be successfully restored by fixed partial prostheses.

Removable Partial Prosthodontics - Quality Evaluation Criteria