Good morning

Presented by: Dr. Sukhjit Kaur

Introduction Oral implantology (implant dentistry) is the science and discipline concerned with the diagnosis, design, insertion, restoration, and/or management of alloplastic or autogenous oral structures to restore the loss of contour, comfort, function, esthetics, speech, and/or health of the partially or completely edentulous patient.

Implant prosthodontics is the branch of implant dentistry concerning the restorative phase following implant placement and the overall treatment plan component before the placement of dental implants.

Differences between natural teeth and implants

Natural toothImplant Surrounding tissuePeriodontal ligament (PDL)OsseointegrationMalocclusionMay be uneventful for years Crestal bone lossNon-vertical forces Relatively toleratedTraumatic to supporting boneLoading-bearingcharacteristicsShock-absorbing function, Stress distributionStress concentrated at crestal boneMovement patternsPrimary: Immediate movement (non-linear and complex)Secondary: Gradual movement (linear and elastic)Gradual movement(linear and elastic)Fulcrum to lateral forcesApical 1/3 of rootCrestal boneLateral movement56~108 m10~50 mApical movement25~100 m3~5 mSigns of overloadingPDL thickening, mobility, wear facets, fremitus, painScrew loosening or fracture, abutment or prosthesis fracture, bone loss, implant fractureTactile sensitivityHigh (proprioceptive feedback mechanism)Low (osseoperception)

Advantages of implant-supported prostheses

1. Maintained bone2. Teeth positioned for esthetics3. Maintained vertical dimension4. Proper occlusion5. Direct occlusal loads6. Improved success rates7. Increased occlusal force8. Improved masticatory performance9. Increased stability and retention10. Improved phonetics11. Improved proprioception12. Reduced palate or flanges

TREATMENT PLANNINGThe ideal implant treatment plan is based on the patient's needs, desires, and financial commitment.

Topdown planningTopdown planning refers to determining the restorative treatment plan and considering all treatment options before developing the necessary surgical treatments. In this way the treatment plan will be developed with the final goal in mind.

Prosthodontic Classification (Misch)FP-1 Fixed prosthesis; replaces only the crown, looks like a natural tooth.

FP-2 Fixed prosthesis; replaces the crown and a portion of the root; crown contour appears normal in the occlusal half, but is elongated or hypercontoured in the gingival half.

FP-3 Fixed prosthesis; replaces missing crowns and gingival color and portion of the edentulous site; prosthesis most often uses denture teeth and acrylic gingiva, but may be porcelain to metal.

RP-4 Removable prosthesis; overdenture supported completely by implant.RP-5 Removable prosthesis; overdenture supported by both soft tissue and implant.

PROSTHETIC EVALUATION IN IMPLANT DENTISTRY1. Interarch space: The implant drills and implant body insertion often require a posterior interarch space of more than 8 mm from the ideal plane of occlusion.

Type of restoration Anterior PosteriorFixed8-10 mm7 mm.Removable12 mm12 mm

2. Implant permucosal position: The ideal position is directly under the incisal edge position of an anterior tooth and under the central fossa of posterior teeth out of the esthetic zone.

The maxillary premolars: the implant body should be positioned buccal to the central fossa to enhance cervical esthetics without hygienic compromise.

3. Existing occlusal plane: The position of horizontal occlusal planes should allow harmonious occlusion with maximum occlusal interdigitation and, canine or mutually protected occlusion on the anterior teeth in all excursions.

A steep incisal guidance may help avoid posterior interferences in protrusive movements. If its shallow, it may be necessary to plan recontouring or prosthetic restoration of any posterior offending teeth. A mesially tipped mandibular third molar may greatly compromise the implant placed in the maxillary posterior region. Aids to evaluate the required changes:Pretreatment diagnostic wax up. Occlusal plane analyzer.

4. Arch relationship: An improper skeletal position may be modified by orthodontics and/or surgery. Implants are placed lingual to original incisal position. Final restoration is over contoured for Esthetics speech lip position occlusion This may result in cantilevered force on the anterior implant body. To compensate for the increase in lateral loads and moment of force, either additional implants or increase in the anteroposterior distance between implants is planned. An anterior cantilever on implants in the mandibular arch may correct an Angles skeletal class II jaw relationship.

5. Arch form: (ovoid, tapering, square) The square arch form provides a poorer prognosis than a tapered arch form. The tapering arch form of residual bone is favorable for anterior implants supporting posterior cantilevers. The square arch form of teeth is preferred when canine and posterior implants are used to support anterior teeth in either arch. The ovoid arch form has qualities of tapered and square arches.

6. Existing occlusion: The partially edentulous posterior ridge with facial resorption may require implant insertion more medial in relation to the original central fossa of the natural dentition.

Enameloplasty of the stamp cusps of the opposing teeth often is indicated to redirect occlusal forces over the long axis of the implant body. The relationship of centric occlusion to centric relation is to be noted because of Potential need of occlusal adjustments to eliminate deflective tooth contacts, and Evaluation of their potential noxious effects on the existing dentition.

7. Existing prosthesis: The existing prosthesis is evaluated for proper design and the esthetics. If the esthetics is unacceptable to the patient, note the reasons for dissatisfaction. A pretreatment prosthesis may be indicated for patients who are currently unsatisfied with esthetics or have TMJ dysfunction, poor soft tissue health for the support of a removable prosthesis, decreased OVD, or collapse of posterior support. Acceptable preexisting maxillary removable prosthesis is used as a template for implant reconstruction. Lip position and support provided by labial flange is evaluated .

If support is less without flange, a hydroxyapatite (HA) labial onlay graft is usually indicated.

8. Location and number of Missing teeth: The number and location of missing teeth influences the prosthodontic treatment plan of the patient.

Location Implants are warranted whenever the following are missing: canine, lateral incisor, and first premolar; or canine, lateral, and central incisors; or canine, first premolar, and second premolar. When one of those three combinations of teeth is missing, an implant usually is placed in the canine region whenever possible.

The second mandibular molar is not replaced in posterior implant supported prosthesis. The mandibular first molar is designed to occlude with the mesial marginal ridge of a natural second maxillary molar to prevent extrusion.Maxillary second molar implant is mostly indicated because. Poor bone density in the region and need for added posterior support. No risk of Paresthesia. Implants do not extrude especially when they are splinted.

Missing teeth: number Independent implant restorations not connected to teeth cause fewer complications and longer success.

NOT more than two posterior ponticse because greater span between abutments increases the flexibility in the prosthesis and porcelain fracture, cement breakage, or screw loosening in the restoration.

To limit the effect of the law of beams, independent implant prostheses may reduce or eliminate the number of pontics while simultaneously increasing the number of abutments and distributing the forces more effectively.

When two pontics are considered, the thickness of the metal may be increased or Additional grooves on the facial and lingual aspects of the implant abutment. Nonprecious metals deform about 50% less than high noble alloys and therefore may be selected for long-span restorations supported by teeth. However, corrosion factors may be a concern with nonprecious alloys contacting titanium implants, especially with subgingival margins. The final restoration may be segmented (canine to canine and two posterior segments) when the number of implants permits.

9. Lip line: Following lip positions are evaluated. Resting lip line Maxillary high lip line Mandibular low lip line. It is recommended to make the patient aware of these existing lip lines and impress upon them that these lip positions will be similar after treatment.

Resting lip line Especially noted if maxillary anterior teeth are to be replaced. The resting lip positions are highly variable, but in general are related to the patients age. Older patients show fewer maxillary teeth at rest and during smiling but demonstrate more mandibular teeth during sibilant sounds. Extending crown height in maxilla to decrease the age of smile may result into increased moment of forces.

Maxillary high lip line. It is determined while the patient displays a natural, broad smile. If patient has high lip position during smiling, the prosthodontic requirements are more demanding e.g. Onlay grafts of HA may be indicated. Addition of pink porcelain.

Mandibular low lip line. It has to be observed during speech. In pronunciation of the s sounds, or sibilants, some patients may expose the entire anterior mandibular teeth and gingival contour.

10. Mandibular flexure: The amplitude of the movement is 0.8 mm in molar area and 1.5 mm in ramus area. As a consequence, complete cross-arch splinting of posterior molars with rigid, fixated implants is usually contraindicated in the mandible

Options Segment the restoration in 2 or more independent prostheses. Non rigid connectors Insert posterior implants only in one section.

11. Temporomandibular joint status Maximal opening is noted Normal 38-40 mm from maxillary incisal edge to mandibular incisal edge in Angles skeletal class I patient. Deviation on opening should be noted. The patient should be able to perform unrestricted mandibular excursions. Patient should ideally be free of symptoms before implant therapy can be considered. Many patients with soft tissue prosthesis and TMJ dysfunction benefit from the stability and exacting occlusal aspects provided by the implant therapy.

12. Soft tissue support Evaluation of soft tissue support is primarily needed in planning for overdenture prostheses.

OUTLINE OF IMPLANT TREATMENTSSURGERYIMPRESSIONSPROSTHETIC RESTORATION

SURGERY Prior to surgery, the implant site is carefully examined clinically, radiographically and using mounted diagnostic casts.Diagnostic Casts Mounted study casts and a diagnostic wax-up are the foundation for determining implant location.Surgical Guide Templates This guide dictates to the surgeon the implant location that offers the best support for the prosthesis, as well as optimal esthetics and hygiene requirements.

Clinical examination: evaluation of Biological width and to determine biotype. The biotype of the gingiva usually is called thick or thin.

Thicker tissue is more resistant to the shrinkage or recession and often leads to the formation of a periodontal pocket after bone loss.

Thin gingival tissues around the teeth are more prone to shrinkage after tooth extraction and more difficult to elevate or augment after tooth loss.

Gingival recession is the most common esthetic complication after anterior single-tooth extraction and is also a concern after implant surgery and uncovery.

Two-stage Surgical ProtocolsSingle-stage Surgical Protocol Before going ahead with implant uncovery, rigid fixation/ osseointegration must be ascertained.In addition to rigid fixation, other factors that should be confirmed at this time include:Absence of crestal bone lossAbsence of painAdequate zone of keratinized gingivalSulcus depthAbsence of inflammationProper hard-and soft-tissue contour.

IMPLANT IMPRESSIONS Accurate recording of spatial implant position is required to obtain a proper support to definitive restoration with passive fitting.

The purpose of Impression in implant dentistry is to record:1. Position.2. Depth.3. Axis/Angulation.4. Rotation-Hex position5. Soft Tissue Contour (Emergence Profile)

COMPONENTS NEEDED FOR MAKING IMPRESSIONS AND CASTS OF IMPLANTSIMPRESSION COPINGSGUIDE PINSIMPLANT ANALOG/ REPLICAABUTMENT ANALOG / REPICAABUTMENT CLAMPSCREW DRIVER

What is impression coping?That component of a dental implant system used to provide a spatial relationship of an endosteal dental implant to the alveolar ridge and adjacent dentition or other structures. Impression copings can be retained in the impression or may require a transfer (termed an indirect transfer procedure) from intraoral usage to the impression after attaching the analog or replicas

any device that registers the position of the dental implant or dental implant abutment relative to adjacent structures.G.P.T-8

Types of impression copingsBased on the method by which they are incorporated/transferred into the impression

pick up coping/direct transfer coping

indirect Tranfer coping / reseating coping

Based on the materials used in their fabrication Metallic

plastic

ABUTMENT ANALOG ?A replica of the superior portion of a dental implant. Usually used to provide an exact form of the dental implant abutment within the dental laboratory during fabrication of a prosthesis supported in part or whole by the dental implant

DENTAL IMPLANT ANALAOG ?A replica of the entire dental implant, not intended for human implantation.

It is used in the casts as a replica of implant on which lab procedures are done.

There are three types of impressions in implant dentistry:Prepared Abutment An intra-oral impression is made of prepared abutment(s), similar to a standard crown & bridge impression.

Implant-level Impression An intra-oral impression is made transferring the emergence of the implant. The implants location and angle are recorded, with or without the orientation of the internal hex.

Abutment-level Impression An intra-oral impression is made of abutments that have been placed onto the implants. Abutment location and angle are recorded for screw-retained prosthesis

Implant-level and abutment-level impressions can be made by either of the following techniques:Closed Tray (Indirect) Transfer Technique orOpen Tray (Direct) Pick-up Technique Prepared Abutment impressions are always made using the Closed Tray technique.

IMPRESSION MATERIAL SELECTIONImpression material that flows to capture the connection of the implant and abutment, and accurately represents the surrounding tissue, is the key to beautiful implant restorations. The ideal impression material has the following desirable qualities:It should accurately represent the tissue in every instance. Have excellent flow, high tear strength, and dimensional stability, like a vinyl polysiloxane (VPS). hydrophilic with good wetability, like a polyether. A vinyl polyethersiloxane (VPES) material combines traits of both a VPS and a polyether for implant impressions. A VPES is reported by the manufacturer to be intrinsically hydrophilic, flowing well even in difficult-to-isolate areas.

Implant Impression Trays

Metal trays are preferred over plastic due to their rigidity.Perforated or not. In non-perforated trays, use tray adhesiveRim lock trayCustom trays

Note:

Uniform thickness of material throughout the tray yields good results.Custom trays present higher accuracy as compared to the impressions obtained with stock trays.If Implant is placed deep, to take transfer type: use small Diameter impression post.Always remove healing abutment and immediately place the impression post. Put them in order.It is important to take a periapical X-ray to verify the fit between the transfer coping and the implant.Verify the seating of components.

In case of improper interface, note small gap between impression post and implant analogue.Ensure that impression post and implant analog are securely screwed together and fully seated in impression.Inhibition of the polymerization of vinyl polysiloxane (VPS) impression materials has been reported to occur with the use of latex protective barriers such as gloves.

Implant Level Impressions: steps common to all impression techniquesRemove the Healing Abutment with the Hex Driver. Make sure that the implant prosthetic platform is free of bone and soft tissue.The emergence of the impression coping selected should match the emergence of the Healing Abutment and the intended final abutment (either narrow, regular or wide). When placing impression copings on multiple implants, remove one Healing Abutment at a time, replacing it immediately with the impression coping. This reduces the likelihood of soft tissue collapsing onto the implant. Work from the posterior to the anterior.

Closed Tray (Indirect) Transfer TechniqueSeat the Indirect Transfer Coping and secure it with the screw (hand-tighten). If practical, orient the flat side of the abutment/ coping to the facial for easier indexing. Take a radiograph along the long axis of the implant to ensure the coping is fully seated.

Advantages of Closed TrayEasierSuitable for short inter arch distance.Visual fastening of the analog to the coping is more accurate

Disadvantages of Closed Tray Inaccuracies with recovery and subsequent deformation of impression material may be encountered with nonparallel implants. Not Suitable for deeply placed implants.

Open Tray (Direct) Procedure

Advantages of Open Tray Reduces the effect of the implant angulation Reduces the deformation of the impression material Removes the concern for replacing the coping back into its respective space in the impression. Disadvantages of Open Tray1. The chairside modification of a stock tray over multiple impression copings is a difficult, time-consuming and messy process. 2. Intra-oral fabrication of an acrylic scaffold to attach the impression copings together is very time consuming and frustrating. 3. The length of the guide screws make it difficult for the clinician to obtain enough intra-oral space to get the driver engaged into the top of the guide screws in the posterior area of the mouth. 4. Even if the impression is clinically acceptable, the impression copings may have some play with respect to one another.

ABUTMENT-LEVEL IMPRESSIONCLOSED TRAY/ INDIRECT TRANSFER TECHNIQUE

OPEN TRAY/ DIRECT/ PICK-UP TECHNIQUE for abutment level impressions

Splinting of impression copingsThe multiple implants can be splinted using an acrylic shim, acrylic resin scaffold or dental floss reinforced with pattern resin or acrylic resin. The materials used to splint copings are composite resin, plaster, acrylic resin or pattern resins.The advantage of pattern resins is their faster polymerization, thus reduced chairside time. Also the exothermic reaction is much less compared to acrylic resin.

Complete arch implant impression technique(J Prosthet Dent 2012;107:405-410)

Future TrendsOptical impressionsCERECScannable abutmentsScans can be prepared in two ways:without scan spraywith scan spray

Factors affecting accuracy of impression:Splinting or not splinting impression copings (the most significant factor)Implant angulation; The number of implants; Polymerization shrinkage of the impression material; The setting expansion of stone; and The design and rigidity of the impression tray.Machining tolerance: Ma et al reported the measured tolerances ranged from 22 m to 100 m.

TRANSFER OF SOFT TISSUE DETAILSeveral techniques for the accurate transfer of the intraoral peri-implant soft tissue developed by a provisional restoration may be summarized as follows:1. fabrication of a customized impression coping that is adapted to the peri-implant soft tissue profile2. use of provisional restoration as an impression coping3. injection of impression material around a provisional restoration seated on a master cast.

Accurate Transfer of Peri-implant Soft Tissue Emergence Profile from the Provisional Crown to the Final Prosthesis Using an Emergence Profile Cast (J Esthet Restor Dent 19:306315, 2007)The provisional crown connected to the laboratory analog inserted in the emergence profile impression prior to pouring.

A trayless impression technique for complete arch implant-supported immediately loaded provisional and definitive restorations (J Prosthet Dent 2005;94:202-3.)

TEMPORARY PROSTHESIS Temporary restorations are dependent on the treatment plan, the requirements of the patient and the final restoration planned.Temporization Prior to Second-stage SurgeryTotally edentulous patient1. The existing denture is relieved over the implant sites and relined with a soft material.2. Transitional implants may be placed in between the permanent implants.

Partially edentulous patient1. A removable prosthesis can be made which is relieved to protect the implant from function.2. A Maryland bridge can be fabricated.3. In non-esthetic zones a temporary may not be necessary.

Temporization After Second-stage SurgeryCement-retained crown & bridgeA provisional crown or bridge restoration can be fabricated on a titanium or PEEK plastic temporary abutment.Techniques used for traditional temporaries on natural teeth are used.

Screw-retained crown & bridge Screw-retained provisional restorations can be fabricated using PEEK plastic or titanium temporary abutments.

ABUTMENT SELECTIONAbutment selection criteria

Angulation (degrees)Interocclusal space (mm)Tissue height(mm)Abutment < 15 15-35 35+2.83.54.55.067.5+

Types of abutments:Prefabricated or Custom made abutmentsManufactured abutments are available which vary in flare, diameter, marginal scallop, angulation and height. These abutments can be prepared or re-shaped to a degree to accommodate crown design and location. The restorative clinician should first observe the clinical presentation of the healing abutment and the canal it creates through the soft tissue. Upon removal of the abutment this canal is assessed for width, depth and location.

Custom Abutments A custom abutment is one in which the practitioner must make either a tissue or a bone-level impression of the implant with the help of a transfer impression coping. Custom abutments are the most universally used due to the variations in biologic width, occlusion, and aesthetic demands of patients. Custom abutments can be modified to allow for sufficient material placement to compensate for occlusal differences. the most efficient and the most costly. If the aesthetic demands of the patient are high, zirconia abutments can be used. If a custom abutment is used, the size of the platform of the implant is recorded and a transfer coping is selected based on an open or closed tray design.

Prefabricated abutments A prefabricated abutment is machine made, seated and torqued atop the implant, prepared as needed, and treated as a conventional post-and-core restorative treatment procedure. The use of the prefabricated abutment reduces both the cost and number of visits.

Contraindications: 1) insufficient interocclusal space, where the abutment would not have sufficient height to retain a crown; 2) the implant requires an angle of correction greater than 15; 3) the collar height (the distance between the implant platform and the gingival margin) is more than 1 mm greater than the largest collar height offered by the manufacturer; and 4) the need for splinting three or more implants in a quadrant when parallelism is required.

Standard prefabricated Abutment When the occlusion is straightforward, the biologic width without impingement and aesthetics are not paramount; standard abutments are sufficient for the final restoration. Titanium alloys and zirconium. A fixed collar height 360 for posteriors or a variable collar height (lower on the facial, higher on the lingual), called an esthetic abutment, for both anteriors and bicuspids. For ease of impression making, selection of an abutment with a collar height that is within 0.5 mm to 1 mm of the maximum cuff height measurement is obtained. This facilitates the placing of retraction cord. A collar height no greater than 1 mm subgingival of the lingualgingival height, may also leave the practitioner with a supragingival finish line in the esthetic buccal (facial) region.

Angulated abutment

The Angulated Prefabricated AbutmentThe implant systems use hexagonal, octagonal or triangular internal mechanism, therefore allowing a number of options for the correction of a malpositioned implant. Straumann synOcta allows 16 different positions of the angulated abutment. However, an angled abutment can only be used if the correction is within 15 to 20.

Selection of the Prefabricated Abutment After removing the healing abutment, the implant restorative platform is exposed. The periodontal probe is then used as a guide. The angle of the implant and how it relates occlusally to the opposing dentition can be determined visually by having the shaft of the probe exit the center of the implant. If the decision has been made to use a prefabricated abutment, the following must be recorded: 1) the diameter of the implant platform (e.g, narrow, regular, or wide, determined from your referring surgeon); 2) the collar or cuff height (the distance between the implant platform and the gingival margin) at the mesial, distal, buccal, and lingual locations; 3) the interocclusal height (the distance between the implant platform and the opposing dentition); and 4) whether a straight or angled abutment is needed.

Preparation of the Prefabricated AbutmentThe preparation of prefabricated abutments in the oral cavity should be avoided whenever possible. The preparation of the prefabricated abutment can be performed, for the most part, outside of the oral cavity. Using a #1556 carbide bur (round-ended cross-cut fissure bur), depth cuts are placed along the buccal aspect of the abutment marking the estimated gingival finish line. Also, a depth cut is placed estimating the occlusal height. The occlusal height must be at least 1.5 to 2 mm below the opposing arch and at least 1 mm from the marginal ridges of the ipsilateral teeth in order to receive an adequate esthetic result.

The abutment is now removed from the oral cavity and is ready for indirect preparation. The depth cuts are connected while establishing a chamfer finish line to the depth of the bur. Then polish using a rubber wheel or any polishing wheel.The abutment is now torqued into position The abutment is now treated as a conventional crown-and-bridge procedure. Retraction cord is placed and an impression is made. A provisional can also be fabricated at this time to protect the abutment.

CAD/CAM AbutmentsThe use of computer-aided design technology is available for fabrication of custom abutments e.g.Atlantis VAD (Virtual Abutment Design) is a patented process using 3D-optimized scanning software to generate an exact virtual image of the upper and lower implant-level model. Atlantis abutments are available in zirconia, titanium, or gold-shaded titanium. It is also available for all major implant systems.An alternative for the laboratory using a UCLA abutment (a gold-plastic abutment used for waxing a custom abutment or screw-retained crown) in fabricating a custom abutment.

PROSTHETIC RESTORATIONRESTORATIVE OPTIONSScrew retained restorations indirect, at abutment level: small prosthetic screws hold the restoration to the standard abutment which is itself screwed down onto the fixture.direct, at fixture level: larger abutment screws fixates the restoration directly to the implant

Implant-level, screw-retained restorationsIndications Single or multiple-unit restorations Screw-retained restorations at the implant-level Fixed-detachable (hybrid-type) restorations Totally edentulous or partially edentulous arch Minimal inter-arch space Laboratory fabricated custom abutments Implant-level bar overdenture fabricationLimitations Splinted restorations on implants with divergent angles greater than 10 May restrict optimal occlusion when used for crown & bridge

Advantages Easier to retrieve prosthesis for servicing, revisions and hygiene maintenance Greater control of esthetics Minimal inter-arch space required

Abutment-level Screw-retained Restorations used for a bar-retained and/or supported overdenture case when the treatment plan indicates the cast bar be 1-2mm supra-gingival. The denture is retained by the bar with attachments, i.e. clips or ball attachments. An implant-retained, tissue-supported prosthesis is indicated when there are fewer than four implants in the mandible and fewer than six in the maxilla.

Indications Multiple-unit restorations Abutment-level bar overdenture Fixed-detachable (hybrid type) restorations Extensive bone loss Thick tissue

Limitations Limited inter-arch space to accommodate abutments, bar and overdenture

Advantages Bar overdenture removable by patient for hygiene Fixed-detachable removable by dentist for hygiene

2. Cement-retained restorations cement-retained abutments are connected to implants with abutment screws, and the crowns are cemented to the abutments.Advantages Easier correction of angulation problems. Improved estheticsWhen multiple implants are splinted, allows for easier, more accurate adaptation.more familiar DisadvantagesExcess cement may be extruded into the tissues causing inflammation, soft tissue problems, and even severe bone loss.Retention may be unreliable.

Direct methodA prefabricated abutment is connected to an implant and prepared intraorally with rotary instruments.

Indirect methodImplant abutments are fabricated in a laboratory on a cast obtained from an implant-level impression

RESTORATION SELECTIONIn the aesthetic zoneIf screw-access is towards the buccal: Cement retained crown or bridgework is almost unavoidable without using a secondary framework Favour flat-fronted CADCAM zirconium abutment if high smileline, thin gum type. Crown margin just below or at gingival level labially. Favour CADCAM titanium abutment if low smileline, or thick gum type. Crown margin just at or just below gingival level labially.

If screw-access is palatal: Screw retained crown or bridgework Favour screw-retained direct to fixture head, porcelain bonded to zirconium if high smileline. If low smileline or thick gum type, favour porcelain bonded to alloy bridgework, screw-retained with intermediate titanium abutment.

Outside the aesthetic zoneIf screw-access is buccal: Cement retained crown or bridgework Porcelain bonded to alloy bridgework custom titanium abutments with margins just at gum line labially. All ceramic individual crowns custom titanium abutments. Crown margin just at gingival level.If screw-access is occlusal/palatal: Screw-retained crown or bridgework Porcelain bonded to alloy bridgework intermediate titanium abutment. Porcelain bonded to zirconium for crown or bridgework screw retained directly to fixture head.

Removable implant-supported prosthesisAdvantages 1. Fewer implants are required.2. Prosthodontic appointments are less complicated, and treatment is less expensive.3. There is improved hard and soft tissue evaluation and access for routine procedures.4. Long-term maintenance or treatment of complications is facilitated, and daily homecare conditions are improved.5. Esthetics is much easier to control for labial flange and denture teeth than customized metal or porcelain. The labial contours may replace lost bone width and height and support the labial soft tissues.6. The prosthesis can be removed at night, to help treat parafunction or implant sensitivity.

LOADING OF IMPLANT PROSTHESISBranemarks protocol : Delayed loading : Progressive loading :Early loading :Immediate loading :Final prosthesis after 3-6 months of initial healing 1stage 2stage Loading 3 months after implant placement Provisional prosthesis brought progressively into occlusion Between 2 wks 3 months Within 2 weeks of implant placement loading is done Functional : Temporary restoration on the same day of surgery in occlusion Non-functional : Not in occlusion

Progressive loading appointments for a cement-retained prosthesis:

StepProcedureDietOcclusal materialOcclusal contacts1.Healing abutmentspreliminary impression Soft002Transitional prosthesis I Final impression SoftAcrylic none 3Transitional prosthesis II Metal try-in; modify transitional prosthesis IISoft Acrylic contact only on implant; no contact on cantilevers/pontics;occlusal table same as final prosthesis4Final prosthesisAdjust occlusion HarderMetal or porcelainOcclusion follow implant-protective occlusion guidelines; narrow occlusal table5Final prosthesisFinal cementationNormalMetal or porcelainSame as above

Additional clinical procedures in partially and completely edentulous residual ridges for implant-supported prostheses

Occlusal rim fabrication Tray material adapted Must engage undercut in gold cylinder/coping Double thickness resin on lingual area Clear facial areas of acrylic resin around brass replicas & copings exposing their interface Guide pins reinserted ,accuracy of abutment copings interface verified Occlusion rim fabricated Access to guide pin created thro the surface of wax rim

Maxillomandibular relationsMandibular occlusal rim stabilized with gold copingsCentric relation recordProtrusive recordFacebow registrationTooth shade, denture tooth mold & occlusal scheme

Esthetic trial fittingCasts mounted on semiadjustable articulatorAnterior & full tooth trial fitting used to established esthetics, phonetics, lip support, VD.CR verified with interocclusal records.Max distal extension cantilever -15mm distal to the distal most, fixture abutment interface bilaterally.

Maximum distal extension cantilever -15mmModified by factors (10 mm)Arch form of abutment: fixture placement in a straight line places more load on the fixtures, abutment screws, and all components than does placement with an arch form.Implant length & prognosis: distal fixtures shorter than 10mm (or those placed in less than ideal bone) limit load potential.Natural opposing dentitionParafunctional habits

Vertical hole drilled through selective teeth to gain access to underlying fixture.Alignment of implant fixture is determined by guide pin.Jaw relation & occlusal contact reconfirmed

The distance from the midline is measured to the most posterior left and right fixtures and is then recorded.The shortest measurement is used and added to the maximum allowable extension. This calculation is the maximum limit of the cantilever section of the implant prosthesis.

OCCLUSION IN IMPLANT PROSTHESESOcclusal overload and its relationship to implant overload and failure is a well-accepted phenomenon. The choice of an occlusal scheme for implant-supported prostheses is broad and often controversial. Almost all concepts are based on those developed with natural teeth and are transposed to implant support systems with almost no modification.

Implant Protective Occlusion: Implant-protective occlusion (IPO) was presented previously as medial positioned-lingualized occlusion and developed by Carl E. Misch. This occlusal scheme is a combination of various principles which need to be addressed when fabricating implant supported prosthesis.

Components of implant protective occlusion:No premature occlusal contacts or interferences: timing of occlusal contactsInfluence of surface areaMutually protected articulationImplant body angle to occlusal loadCusp angle of crowns (cuspal inclination)Cantilever or offset distance (horizontal offset)Crown height (vertical offset)Occlusal contact positionsImplant crown contourProtect the weakest componentOcclusal materials

Timing of occlusal contacts: S =F/A. Therefore during maximum intercuspation and centric relation occlusion, no occlusal contacts should be premature, especially on an implant-supported crown.

whether a rigidly fixated implant may remain successful when splinted to natural teeth!!!!!!! The implant prosthesis should barely contact, and the surrounding teeth in the arch should exhibit greater initial contacts. Only light axial occlusal contacts should be present on the implant crown. Contacts should be of similar intensity on the implant crown and the adjacent teeth when under greater bite force because all the elements react similar to the heavy occlusal load.

Influence of surface area:When implants of decreased surface are subjected to angled or increased loads, place an additional implantin the region of concern.The conventional ratio of implant to prosthetic unit is 1:1. However, for posterior restorations, the ratio may vary. Two implants can be placed in narrower ridges and will provide greater anti-rotational and occlusal support and an increased surface area for osseointegration. Two implants positioned off angle will also provide counter support and reduce stress on the angled abutment screws.The implant crowns can be splinted together, so that the surface area of support is increased. Wider-diameter root-form implantshave a greater area of bone contact at the crest than narrow implants tplacement of implants in the posterior jaws to be staggeredto improve biomechanical resistance to loads.

Mutually protected articulationThe posterior teeth are protected by the anterior guidance during excursion, whereas the anterior teeth have only light contacts and are protected by the posterior teeth in centric occlusion. This concept is called the mutually protected articulation.The anterior guidance of implant prosthesis with anterior implants should be as shallow as practical

Implant body orientation and influence of load direction: Implants are designed for long-axis loads. An axial load over the long axis of an implant body generates a greater proportion of compressive stress than tension or shear forces.IPO attempts to eliminate or reduce all shear loads to the implant-to-bone interface. The greater the angle of the force, the greater is the shear component. Because shear forces are increased with an angled load to the implant body, an attempt is made to reduce the negative effect of angled loads.

Crown cusp angleThe angle of force to the implant body may be influenced by the cusp inclination. The occlusal contact over an implant crown therefore should be ideally on a flat surface perpendicular to the implant body. This position usually is accomplished by increasing the width of the central groove to 2 to 3 mm in posterior implant crowns, which are positioned over the middle of the implant abutment. The opposing cusp is recontoured to occlude the central fossa directly over the implant body.

Cantilevers and implant-protective occlusion The weakest link in the cantilever design is the location and size of the pontic and the intensity of occluding masticatory forces. These forces tend to be greatest in distally located pontic cantilevers.A mesial cantilever is favored over a distal cantilever for this reason. A narrow occlusal table is recommended for the pontic. to reduce the force on the lever or pontic region compared with that over the implant abutments.no lateral load is applied to the cantilever portion.Although the ideal restoration is completely implant supported, to reduce the effect of cantilever, the natural teeth must be evaluated for potential abutment(s).

Permissible cantilever extension for implant supported prosthesis according to various authors:Branemark 2-3 premolarsZarb and Schmitt- 20mmTaylor and Bergmann- 20mm(5-6 abutments) and 15mm(4 abutments)Rangert et al- 15-20mm in mandible and 10mm in maxillaEnglish- 1.5xA-P spread

Crown height and implant-protective occlusionThe implant crown height is often greater than the original natural anatomical crown, even in Division A bone.

Crown height with a lateral load may act as a vertical cantilever and a magnifier of stress at the implant-to-bone interface.

The greater the crown height, the greater the resulting crestal moment with any lateral component of force, including those forces that develop because of an angled load.

The noxious effects of a poorly selected cusp angle, an angled implant body, or an angled load to the crown will be magnified by the crown height measurement.

Occlusal contact positionsThe number of occlusal contacts in an occlusal scheme varies. Occlusal contact position determines the direction of force, especially during para function. An occlusal contact on a buccal cusp and marginal ridge contact is the cantilever load. The ideal implant body position is usually directly under the central fossa and may be 1 to 2 mm to the facial aspect (when bone is abundant) to be under the buccal cusp of the mandible and to improve the esthetic emergence of maxillary implant crowns. The ideal primary occlusal contacts therefore will reside within the diameter of the implant, within the central fossa. Secondary occlusal contacts should remain within 1 mm of the periphery of the implant to decrease moment loads. Marginal ridge contacts should be avoided.

Implant crown contourRestorations mimicking the occlusal anatomy of natural teeth often result in offset loads (increased stress), complicated home care, and increased risk of porcelain fracture. An over contoured anterior or posterior restoration will also act as a cantilever and increase stress within the framework during loading. The abutment selection should compensate for minor irregularities in implant angulation to help compensate for occlusal factors. A wider occlusal table will increase stress on the abutment screws. As a result, in non-esthetic regions of the mouth, the occlusal table should be reduced in width compared with natural teeth.

Design to the weakest archAny complex engineering structure typically will fail at its weakest link, and dental implant structures are no exception. Thus all treatment planning decisions for IPO should be based on careful consideration of 1) identifying the weakest link in the overall restoration and 2) establishing occlusal and prosthetic schemes to protect that component of the structure.

Occlusal materialsThe occlusal surface materials selected affect the transmission of forces and the maintenance of occlusal contacts. In addition, occlusal material fracture is one of the most common complications for restorations on natural teeth or implants.

Occlusal materials may be evaluated by esthetics, impact force, a static load, chewing efficiency, fracture, wear, inter arch space requirements, and groups of castings.

The three most common groups of occlusal materials are prostheses on implants are porcelain, gold and resin.

OCCLUSAL MATERIAL CHARACTERISTICS:

Conclusion

Implantology is a prosthetically driven entity. Information Before Treatment is Diagnosis Information after Treatment is an excuse

A good impression is the key to success of the implant prosthesis.

Thank you

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