Modification of tooth contours for removable partial dentures, part II: Invasive techniques

Abstract

When natural teeth are selected as abutments for RPDs, it is often desirable to modify their axial and occlusal contours. Minor modifications to natural tooth contour can be made simply by grinding, but these may be limited if the enamel is thin in the areas requiring modification. In contrast, major modifications to tooth contour can only be achieved by the use of surveyed crowns. Surveyed crowns are cast restorations fabricated for teeth serving as abutments for RPDs. When such restorations are already part of the overall treatment plan of the patient, it is practical to coordinate the design of the restorations with that of the proposed partial denture. The surveyed crowns have in common the requirements which may be summarized as follows: occlusal rest seat and satisfactory occlusion, suitable guide planes, suitable retentive undercuts, suitable reciprocal elements areas. It is essential that the surveyed crowns incorporate space for the partial denture components. The crowns themselves should be waxed up and milled on the surveyor to be in harmony with the prepared path of insertion and design of the partial denture. Based upon that, the basic aim of this paper would be to describe the clinical and laboratory procedures involved in the production of the surveyed crowns.

Aksijalne i okluzalne površine prirodnih zuba planirane za sidrenje PSP se, najčešće, moraju preoblikovati. Male modifikacije prirodnih zuba mogu se jednostavno izvesti brušenjem, ali su limitirane debljinom gleđi u traženoj regiji. U suprotnom, velike modifikacije oblika zuba mogu se ostvariti namenskim nadoknadama. Kamenske nadoknade su deo terapije i neophodno je prilagoditi njihov oblik PSP. Na namenskim krunicama, kao najčešćim oblicima namenskih nadoknada, treba formirati ležišta za okluzalne naslone ili odgovarajuće stepenike za prenos okluzalnih sila, odgovarajuće vodeće ravni, neophodnu dubinu podminiranosti i ravne oralne površine. Kamenske nadoknade moraju obezbediti prostor za elemente PSP. Frezovanjem u vosku i metalu obezbeđuje se pomenuti prostor i harmonija sa pravcem unošenja proteze i dizajnom buduće PSP. Imajući sve ovo u vidu cilj rada je bio da se opišu fiksne nadoknade namenjene sidrenju PSP.