1/29/2016 PART 6 Implant Prosthodontics 26/11/2015 LIMU Dr. Rafik M. Alkowafi 188 1- Single tooth implant prosthodontics • In many respects the prosthodontic treatment for a single tooth is straightforward if the planning and placement of the implant is correct. • If implant positioning is poor, the prosthodontic correction of the error to achieve an acceptable result can be impossible. • The choice of the appropriate single tooth abutment is one of the most important prosthodontic factors. 26/11/2015 LIMU Dr. Rafik M. Alkowafi 189 1
1/29/2016 1- Single tooth implant prosthodontics • Abutment types: – All manufacturers produce a variety of abutments suitable for single tooth restorations. Abutments attach the crown to the implant and prevent rotation between components. – The final restoration needs the correct emergence profile to support and contour the soft tissue. This may require a transition from a standard 4-mm-diameter implant to the 7-mm-wide neck of a central incisor for example. – The abutment needs to resist conventional compressive and tensile loads and rotational forces, as it will not be joined to other implants or teeth. 26/11/2015 LIMU Dr. Rafik M. Alkowafi 190 1- Single tooth implant prosthodontics • Choosing the Abutment: – Abutment selection is based on the following features. 1. Depth of Soft Tissue 2. Emergence Profile 3. Orientation 4. Interocclusal Space 5. Retrievability 6. Special Aesthetic Requirements and final restoration. 26/11/2015 LIMU Dr. Rafik M. Alkowafi 191 2
1/29/2016 1- Single tooth implant prosthodontics Abutments for single tooth restorations fall into the following categories: 1. Standard abutments (readymade) 2. Semiprepared abutments 3. Fully customized abutments 4. Computer-generated abutments [computer- aided design (CAD)/computer-aided manufacture (CAM)] 5. Prepable abutments 6. Abutments for screw-retained crowns 26/11/2015 LIMU Dr. Rafik M. Alkowafi 192 1- Single tooth implant prosthodontics 26/11/2015 LIMU Dr. Rafik M. Alkowafi 193 3
1/29/2016 1- Single tooth implant prosthodontics 1. Standard Abutments: • They are usually two pieces with an abutment that fits onto/into the implant head and a separate abutment screw that can be titanium alloy or gold alloy. • A variety of heights are offered with a smooth collar that extends from the implant head to the margin for the crown. • Matched impression copings, temporary copings, laboratory Selectionof abutment height. (A) A short abutment analogues, and gold and collar places the margin deeper in the soft tissues but porcelain cylinders are produced allows more height for development of a suitable to ease manufacture. emergence angle compared to a longer-abutment collar height (B). 26/11/2015 LIMU Dr. Rafik M. Alkowafi 194 1- Single tooth implant prosthodontics • Advantages/Indications of Standard Abutments 1. Simple to use 2. Minimal chairside and laboratory time 3. Predictable fit and retention for crown 4. Use in “straightforward” cases where optimal space and implant orientation has been achieved • Disadvantages/Contraindications of Standard Abutments 1. Margin for crown does not follow gingival contour 2. Cannot be customized for implant orientation or anatomical features — particularly not suited to very labially inclined implants 3. Not suitable for multiple adjacent single tooth restorations as the path of insertion of the crowns is not adjustable. 4. Not suitable for extremes of interocclusal space 26/11/2015 LIMU Dr. Rafik M. Alkowafi 195 4
1/29/2016 1- Single tooth implant prosthodontics 2. Semiprepared Abutments • These abutments are similar to standard abutments but have a more anatomic shape and are designed to be modified in the laboratory to customize the shape for differing clinical situations. • This includes abutments with angulation changes built in. The abutments have a contoured gingival margin to allow for a deeper margin on the labial aspect in the aesthetic zone and this can be The coronal portion of the abutment can 26/11/2015 LIMU Dr. Rafik M. Alkowafi 196 1- Single tooth implant prosthodontics • Advantages 1. Allows for changes to angulation and crown path of insertion 2. Gingival margin contours can be followed 3. Minimal laboratory input • Disadvantages 1. Customization limited by size of abutment at start 2. Circular in cross section so not able to fully simulate anatomic contours 3. Require abutment selection at start (i.e., multiple sizes/ shapes) 26/11/2015 LIMU Dr. Rafik M. Alkowafi 197 5
1/29/2016 1- Single tooth implant prosthodontics 3. Fully Customized Gold Abutments • The abutments have a readymade precious metal component that is the abutment/implant connection corresponding to the implant design. This ensures a perfect fit between abutment and implant. • The rest of the abutment is a plastic customizable cylinder that the laboratory technician can wax on to. The plastic cylinder is a burnout plastic so the whole abutment shape apart from the fit part is fully customizable by the laboratory technician who can then cast the abutment using conventional techniques 26/11/2015 LIMU Dr. Rafik M. Alkowafi 198 1- Single tooth implant prosthodontics • Advantages 1. Suitable for cemented and screw-retained restorations 2. Fully customizable including angulation 3. Works for extremes of interocclusal space 4. Easy to align multiple implants • Disadvantages 1. Gold abutments only 2. Expensive and complex laboratory input required 26/11/2015 LIMU Dr. Rafik M. Alkowafi 199 6
1/29/2016 1- Single tooth implant prosthodontics • The nonsegmented implant crown (sometimes termed a “UCLA” restoration as it was first described at the University of California, Los Angeles) bypasses the abutment portion by means of a sleeve waxed directly to the implant. • Using nonsegmented implant crowns may be necessary when soft tissue thickness is less than 2 mm. 26/11/2015 LIMU Dr. Rafik M. Alkowafi 200 1- Single tooth implant prosthodontics 4. Computer-Generated Abutments • Several manufacturers have systems available to make abutments, which are fully customized using CAD/CAM techniques • The abutments are produced as part of a • factory process so quality control is high. • Particular advantage is the ability to produce abutments that are fully customized in ceramic (zirconia) and titanium. 26/11/2015 LIMU Dr. Rafik M. Alkowafi 201 7
1/29/2016 1- Single tooth implant prosthodontics • Advantages 1. Fully customized abutments in titanium and zirconia 2. High precision • Disadvantages 1. Require specialist facilities 2. Expensive 26/11/2015 LIMU Dr. Rafik M. Alkowafi 202 1- Single tooth implant prosthodontics 5. Prepable Abutments • Prepable abutments are solid abutments normally made from titanium or titanium alloy that are customized by preparing them with a drill, normally in the laboratory but sometimes in the mouth, into a “crown preparation. ” 26/11/2015 LIMU Dr. Rafik M. Alkowafi 203 8
1/29/2016 1- Single tooth implant prosthodontics • Advantages 1. Improved flexibility over standard abutments 2. Copes with angulation changes • Disadvantages 1. More complex laboratory technique than standard abutment 2. Customization limited to the basic size/position of the 3. May require second intraoral impression 4. Precision of fit of crown to abutment is less predictable 26/11/2015 LIMU Dr. Rafik M. Alkowafi 204 1- Single tooth implant prosthodontics 6. Abutments for Screw-Retained Crowns • For single tooth, the main advantage is simplicity and ease of insertion and removal. • Problems can arise when cementing crowns, particularly if deep margins are used. With a screw-retained approach, the porcelain can be taken further subgingivally with minimal risks. • Usually screw-retained crowns are more applicable to premolar and molar regions where occlusal screw access may be less of an aesthetic problem • The technique utilizes gold fully customizable abutments that are waxed up to the contour ready for porcelain application so that the abutment and crown are in one-piece. • Gold suitable for porcelain bonding is used. 26/11/2015 LIMU Dr. Rafik M. Alkowafi 205 9
1/29/2016 1- Single tooth implant prosthodontics • Advantages 1. Predictable retention and removal 2. No margins or cement 3. Easy access to abutment screw if tightening required 4. Very robust 5. Takes up less space than conventional two-part technique • Disadvantages 1. Screw hole must exit in suitable position cosmetically 2. Screw hole may make occlusion less stable if in critical occlusal contact position 26/11/2015 LIMU Dr. Rafik M. Alkowafi 206 1- Single tooth implant prosthodontics • Impression Coping • Impression copings facilitate transfer of the intraoral location of the implant to the same position on the laboratory cast. Impression copings can be either screwed into the implant body or screwed or snapped onto an implant abutment. • Typically, the impression transfer can be either closed-tray transfer or open-tray transfer. • The closed-tray technique captures the index of the impression coping, and after the impression is removed from the mouth, the impression coping is unscrewed from the implant and placed along with an implant analog back into the impression. 26/11/2015 LIMU Dr. Rafik M. Alkowafi 207 10
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