# Implant Components and Abutments > Implant components for BDS Prosthodontics: fixture, abutment, screws, connections, platform switching, abutment types and torque picks. - Canonical URL: https://prepelephant.com/topics/bds/prosthodontics/implant-components-abutment - Exam / course: BDS · Subject: Prosthodontics - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Implant Components and Abutments", PrepElephant, https://prepelephant.com/topics/bds/prosthodontics/implant-components-abutment ## Direct answer A two-piece endosseous implant breaks down into the fixture (the threaded, osseointegrated body in bone), the abutment (the transmucosal connector that carries the crown), the abutment screw joining them, and the prosthetic screw or cement that fixes the crown to the abutment. Cover screws seal the fixture's internal threads during submerged healing; healing abutments (gingiva formers) are placed at second-stage surgery to shape the peri-implant soft tissue. The implant-abutment connection is external hexagon (historical, about 0.7 mm), internal hexagon, or conical morse-taper; internal and conical designs move the joint away from the bone crest, resist screw loosening and reduce microgap-related crestal bone loss, and platform switching — seating a narrower abutment on a wider platform — pursues the same end. Abutments themselves arrive as stock titanium cylinders, castable UCLA-type plastic or gold cylinders, custom-cast, or CAD-CAM titanium and zirconia. ## What you must remember - **Component vocabulary for the viva:** fixture, cover screw, healing abutment, impression coping (transfer or pickup), analogue, abutment, abutment screw, prosthetic screw, abutment driver. - **Connection types:** external hex (anti-rotational history, about 0.7 mm), internal hex and conical morse-taper; internal connections concentrate lateral loads within the fixture and show less screw loosening in the literature. - **Platform switching:** a deliberately narrower abutment on the fixture platform, shifting the inflammatory connective tissue zone inward and away from bone, with reduced crestal bone loss reported in many studies. - **Torque discipline:** abutment screws are commonly tightened to manufacturer-specified values around 20-35 Ncm for titanium screws, and prosthetic gold screws to roughly 10 Ncm — undertorquing loosens, overtorquing strips or fatigues. - **UCLA abutment:** the original castable plastic or gold cylinder machined to the implant connection, allowing custom-cast abutment and crown-direct-to-fixture designs for screw-retained restorations. - **Abutment materials:** titanium (workhorse), zirconia (anterior aesthetics, lower plaque affinity), titanium-zirconia alloys; ceramic abutments demand wall thickness and careful handling. - **One-piece implants:** fixture and abutment integrated, used for small-diameter or transitional situations; no screw joint to loosen but no retrievability of the abutment either. ## Following an implant from placement to crown Narrate the timeline with parts named. At stage-one surgery the fixture is placed and a cover screw seals it under the flap, or a tall healing abutment is fitted immediately in single-stage systems. After osseointegration, stage two exposes the fixture and seats a healing abutment to sculpt the emergence contour. At the impression appointment the healing abutment is exchanged for a transfer (closed-tray) or pickup (open-tray) coping; an analogue is attached to the impression and the working cast reproduces the implant position with a gingiva substitute. Abutment selection follows: a stock titanium abutment for a straightforward single crown, a castable UCLA-type or CAD-CAM custom abutment where angulation, emergence or margin depth demands it. The abutment is seated and torqued to specification — around 20-35 Ncm per manufacturer — and the crown cemented over it, or in a screw-retained design joined directly to the fixture through a prosthetic screw at roughly 10 Ncm for gold. Every step is retrievable in the screw-retained version and only destructively so in the cemented one. ## Where students slip The labelling question is the practical classic — a diagrammed implant system with parts to name — and candidates routinely confuse the cover screw (healing phase, under the flap) with the healing abutment (transmucosal, shapes tissue). The viva trap is asking what the microgap does: the implant-abutment junction harbours bacteria and sits near the bone, which is precisely why conical connections and platform switching were engineered, moving the junction inward or away from the crest. The MCQ staples are the external hex height (about 0.7 mm), platform switching, and the torque values attributed to manufacturers rather than universal constants. Indian university theory papers pair this topic with osseointegration basics, and the examiner's discriminating question is why titanium — the expected answer travels through biocompatibility, passivating oxide layer and stiffness compatible with bone, not merely "it is strong". ## Frequently asked questions ### What is the difference between a cover screw and a healing abutment? The cover screw seals the fixture internally during submerged healing beneath the flap; the healing abutment screws on transmucosally after exposure to shape the soft-tissue cuff. ### What is platform switching and why is it used? Seating a narrower abutment on a wider fixture platform, shifting the implant-abutment junction and its inflammatory zone inward and away from the crestal bone, which many studies associate with less marginal bone loss. ### What are the main implant-abutment connection types? External hexagon (historical, about 0.7 mm), internal hexagon and conical morse-taper connections, with internal designs showing better resistance to lateral load and screw loosening. ### What torque values are used for abutment and prosthetic screws? Commonly around 20-35 Ncm for titanium abutment screws and roughly 10 Ncm for prosthetic gold screws, always per the manufacturer's specification, never guessed by feel. ### What is a UCLA abutment? A castable plastic or gold cylinder machined to fit the implant connection, allowing custom-cast abutments and screw-retained crowns connected directly to the fixture platform.