Implantology Guide I.docx

Implantology Guide I-JTN 1.23 Introduction (1.23.2017) Osseointegration: a direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant. Discovery of osseointegration: In the 1950’s and early 1960’s, Professor Branemark was engaged in blood flow...

Implantology Guide I-JTN 1.23 Introduction (1.23.2017) Osseointegration: a direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant. Discovery of osseointegration: In the 1950’s and early 1960’s, Professor Branemark was engaged in blood flow research of the rabbit fibula. Using a titanium chamber, containing an optical system for transillumination of a thin layer of bone/marrow, the blood flow was observed by microscope. The chambers could not be removed from the bone once healed, and the observation of bone growing in intimate contact with the chambers led to the identification of osseointegration as a real biologic phenomenon Branemark is widely acknowledged for his contribution to the scientific discovery and for having creating the term: “osseointegration” Others, prior to Branemark had made the same observation regarding titanium and bone. Notably, Bothe et al, credited as the first to use titanium (1940,) and Leventhal (1951) , in an article titled, “Titanium, a metal for surgery”. Both observed the tendency of titanium to be difficult or impossible to remove from bone, once healing had occurred Important features of design: A.) Shape of the implant: B.) Composition of the implant The original “Branemark” implant was a machine turned implant made of titanium (most common) A popular type of implant at the same time the Branemark came to market was known as a press fit implant One of the first roughened surface implants (press fit implants are hammered or molded into place) with a polished collar that was supposed to stay above the bone Zirconia: derived from zirconium metal (atomic number 40) Produced by a process called reductive chlorination This results in the ceramic Zirconium oxide (this is not a metal), known as zirconia. C.) Surface composition: a roughened surface increases surface area for bone to implant contact by changing the cells involved in osseointegration [these cells can be measured as markers to measure the interaction of the roughened surface and overall osseointegration] alkaline phosphatase (early marker for osteoblast differentiation) osteocalcin (late marker for osteoblast activity) PGE2 prostaglandin (required for osteoblast activity, and cell response to surface structure) TGF-β1 (enhances the mineralization & expression of bone-specific extracellular matrix proteins on implant The roughened surface provides a greater stability in the critical healing phase Result in faster stability (not a higher long term success rate), enabling the restorative treatment to begin earlier [In as little as 3 weeks] An implant must be stable at the moment you place it (there is a dip in stability during the initial weeks of placement) Ways to roughen the surface: Titanium Plasma sprayed Sand blasted large grit acid etched Use of Titanium oxide D.) Connection to prosthesis Thread pitch: the distance between the screw ridges on an implant (the coronal aspect has thread pitches that are tight whereas the apical region has them more widely space) The length of the thread is also important relative to the state of the bone surrounding the area E.) Location of the implant/prosthesis margin relative to bone Cupping: bone loss associated with dental implants (Branemark accepted this bone loss as completely natural and allowed for 2 mm of natural loss) Discovery of the Tissue level implants: the implant had two parts [rough and smooth surface which was supra-crestal to the bone] The abutment was nowhere near the bone level with these implants and therefore resulted in no cupping [this proved that cupping was not natural and did not need to happen] In the one stage approach, the implant/abutment traverses through the mucosal tissue at the time of placement. In the two stage approach, the implant is initially submerged, with the tissue closed coronal to it. The implant will need to be uncovered, and abutment attached at a later date Biologic width: CT inserts onto the tooth surface which does not happen in a dental implant However, we need to establish a distance between the abutment and the crest of the bone (if this distance is not established, the body reacts by making bone loss occur) Platform switching is a method used to preserve alveolar bone levels around dental implants. The concept refers to placing screwed or friction fit restorative abutments of narrower diameter on implants of wider diameter, rather than placing abutments of similar diameters, referred to as platform matching. Digital technology is used using a CBCT scan and an optical scan of patient’s teeth and gingiva Components of the Implant: Implant, abutment, screw that holds the abutment to the crown, and the crown Two types of crowns: cement retained and screw retained (crown and abutment are one piece and what holds them together) Implant platforms: The original Brånemark protocol required several externally hexed implants to restore fully edentulous arches, linking them together via a metal bar with a fixed prosthesis The external hex design was present to help screw the implant into place. In fact, for the fully edentulous, fixed prostheses abutments that were screwed down onto the implants, the hex was not engaged as an anti-rotation device Attachment mechanism: External hex: It resides on the platform Internal hex: It will extend to within the implant body Functions of hex: Acts as a retentive mechanism between implant body and abutment Serves as an effective anti-rotation element (if rotating, then not fully seating) The hex area is the weakest area in the entire implant body-abutment connection Screw loosening and fracture of implant components have been noted more with traditional external hex than with internal hex External connections (hex: hexagon, octa: octagonal) Advantages: Long-term follow-up data are available Compatibility among multiple implant systems Solutions to complications are found throughout the literature due to their extensive use Disadvantages: Higher prevalence of screw loosening Higher prevalence of rotational misfit Inadequate microbial seal Internal connection: (internal hex, Morse taper, 8 point; 12 point contacts, tripod contacts) Advantages: Less screw loosening Improved microbial seal Better joint strength More platform switching options Disadvantages: There is less historical literature on internal connections than external connections Implant that has RN or WN: have a tissue level implant/ NC or RC: bone-level connection for Straumann [all of these are internal hex] Novel Biocare are colored coded and what we will be using in the clinic Natural teeth vs. implants & Forces: The internal stresses that develop in an implant system and surrounding biological tissues under imposed load may have a significant influence on the long term prognosis of the implants in vivo A goal of treatment planning should be to minimize and evenly distribute mechanical stress in the implant system and contiguous bone Factors affecting load bearing capacity of the implant: A.) Implant surface [these 3 talked about in the beginning of the introduction lecture] B.) Implant structure/material C.) Quality of bone to bone D.) Type of load Mainly Vertical and Horizontal (lateral) 1.) Compressive: Tend to push masses towards each other Maintains integrity of bone – implant interface Accommodated best Cortical bone is strongest in compression 2.) Tensile: Pulls objects apart 3.) Shear: Sliding Distract / disrupt bone implant interface Shear forces are most destructive, cortical bone is weakest to accommodate shear forces E.) Shape and dimension of implant Currently available implants vary in diameter from 3 to 7 mm. Finite element studies suggest an implant with a wider diameter is more favorable in reducing the stress distribution in bone surrounding the implants Dental implants length commonly range from 8 to 15 mm. As the length of the surface area increases, it has been suggested that the stress level for a given applied load is reduced on longer implants because of greater surface area An increase in the implant diameter decreases the maximum value of Von Mises equivalent stress which occurs as a result of a more favorable distribution of the simulated average masticatory forces applied in this study When increased diameter and length increased have an increase in all types of load forces Wider diameter implant: Advantages: Allows engagement of a maximal amount of bone Improved distribution of stress in the surrounding bone Allows for the application of higher torque in the placement of prosthetic components Disadvantages: Limited by the width of the residual ridge Esthetic requirements for a natural emergence profile Longer vs. short implants: Study: 525 implants 3.5 to 5.1 mm in diameter 7 to 9 mm for six studies and less than 6 mm for the other two Conclusion: Five-year estimated failure rates were 1.61% and 2.92%, respectively, for extra-short and short implants (this study was in vivo and is more reliable than in vitro) Furthermore, it was found that the wider the implant, the higher the failure rate Factors affecting success of short implants: Specific implant system used Implant surface topography Roughened surface vs Machined surface Implant maximized surface area Surgical protocol Type of prosthesis Single crown vs full arch prosthesis Splinting Occlusion vs cantilever Patient’s medical status Treatment Planning (1.30) Treatment plan: medical and dental history, clinical examination, radiographic analysis Medical history: documentsurgeries, hospitalization, allergies, diseases Medications: NSAIDS (cause abnormal bleeding) IV bisphosphonates: can cause osteonecrosis of jaw Corticosteroid therapy: suppresses immune response, impairs wound healing, and can compromise the normal adrenal response to stresses Review for conditions that might pose a rise for adverse reactions/complications Pregnancy: do in first trimester Do X-rays, anti-inflammatory drugs, antibiotics after surgery Soft and hard tissue intra-oral lesions: Lichen planus, herpes simplex, candidiasis, squamous cell carcinoma Peri-apical lesions, cysts, ameloblastoma, sarcomas of the jaw Contraindications: chemotherapy, osteoporosis, uncontrolled diabetes (will affect wound healing) Must get clearance from their treating physician Social habits: Smoking and tobacco use (affects implant success through effect on bone metabolism) Para functional habits (repeated lateral forces can be detrimental to osseointegration process) Substance abuse (psychological problems, non-complianceimpaired organ function) Restorative work: Oral hygiene status and practices Restorative work, old FMX Compliance (is patient able to clean their own teeth) with past dental recommendations Previous experience with surgery and prosthetics Attitude and motivation towards implants (can get more bone loss on implant than regular tooth) Radiographic analysis: 2D: PA, panoramic radiographs (overview of where things are), cephalometric radiographs (more for ortho) vs. 3D: computed topography and magnetic resonance imaging (not used often in dental practice) Objectives of radiograph: 1.) Rule out presence of disease at proposed surgery site (caries, bone loss, periapical lesions, calculus) 2.) bone quantity (height and width) 3.) bone density (quality) 4.) evaluate relationship of critical structures to the prospective implant sites (nerves, sinuses) 5.) optimum position of implant placement relative to occlusal loads Pre-implant considerations: Existing occlusion, occlusal plane, orientation Occlusal scheme (canine guidance vs. group function) Drifting, lifting, supraeruption Curve of Spee and Wilson Interarch and interproximal space Interarch space: Fixed: 7 mm minimum (TQ) Removable: 12 mm minimum Interproximal distance: Fixed: 6 mm minimum Removable: AP spread Increased space: Cause: due to vertical bone loss Effect: crown to root (implant ratio)forcescomponent and material ftacture Management: grafts before implant placementbetter crown to root ratiobetter esthetics and improved hygiene Decreased space: Cause: migration, supraeruption, abrasion and attrition Effect: decreased retention, (short abutment), poor hygiene, poor esthetics Management: altering VDO, enameloplasty Existing VDO If you restore vertical with implantsmust be bilateral Adding to VDO will add to crown to implant ratio Maxillomandibular arch relationship Skeletal relationshiporthodontic treatment/surgical treatment [want to know if patient is optimal for having an implant in a particular place] Occlusal schemes (forces applied to teeth) TMJ status Pain (muscular tenderness), noise (clicking), limited jaw opening (will interfere with the implant placement) Arch form (anteroposterior distance) Ovoid (most common), tapering (found in class II skeletal patients), square (may result from initial formation of the basal skeletal bone) A/P spread (anteroposterior distance): distance from the center of the most anterior implant to a line joining the distal aspect of the two most distal implants Missing teeth (location and number) Second molarjaw class lever IIIless inter-occlusal spacemore forcesmore lateral interferences Incisoradequate inter-occlusal spaceless forcesbetter esthetics Molars resist vertical forces better and incisors resist horizontal forces better Lip line at rest and during speech: Resting lip line: the resting lip positions are high variable (related to the patient’s age) Older patients show fewer maxillary teeth at rest and during smiling but demonstrate more mandibular teeth during sibilant sounds Soft tissue support Available bone Team approach: surgical-restorative consultation is done prior to implant placement to address [soft tissue management, surgical sequence, implant placement (angulation), need for ridge and soft tissue augmentation, healing time] Surgical Guides (1.30) Accurate placement of the implant is critical to achieving a pleasing esthetic result, as well as the correct alignment for withstanding occlusal forces An implant placement guide also allows for less stressful surgery for the operator, knowing that the critical placement factors were considered in the fabrication of the guide A stable and accurate surgical guide provides a precise reference for implant placement Components: Guiding cylinder: Guides the drill into exact location and orientation Contact surface: Fits either on an element of a patient′s gingiva or on the patient′s teeth/bone Types of surgical guides: Bone supported: surgical guide rests directly on bone (after raising a flap) Mucosa supported: surgical guide rests on mucosa, aided by fixation screws Tooth supported: surgical guide is supported by dentition Fabrication (Technique 1): Diagnostic cast is made Wax-up of proposed implant supported restoration A vacuum shell is fabricated A clear acrylic resin, is poured into the shell then cured Holes are drilled based off of the position on the cast Technique 2: Diagnostic cast is made Wax-up of proposed implant supported restoration Silicone impression of the wax-up is made Acrylic resin, is pored into the mold the cured Holes are drilled based off of the position on the cast Can be done virtually: intra-oral scan, CBCT scan, 3D computer simulation (virtual wax-up), merging of the sets of data, virtual implant placement, designing and fabricating a surgical guide Advantages: More precise placement of implants Preservation of anatomic structures High geometrical accuracy of 0.1 mm s shorter treatment/surgery times Less invasive, flapless surgery and therefore less chance of swelling Less post-operative strain on dentist and patient Transparency of material which allows better visualization Limitations of computer aided surgical guides: Substantial investment of money, time, and effort More knowledge and training required When and Where for Dental Implants (1.30) 3 most important factors: medical history, enough bone, enough space to restore Enough bone to place implant: Length: medial- distal direction Width: buccal- lingual Depth: crestal-apical Implant should be at least 1.5mm from adjacent tooth Implant should be 3mm from adjacent implant At least 1mm of bone on facial and lingual of implant Success rate in D4 is much less than D1 (easier to place a lesser dense bone such as a D2 and D3 as opposed to a D1) Keratinized tissue: preserve at the time of extraction and during the initial incision when placing the implant if 1 stage Increase: prior (place a graft, more efficient) vs. after How to determine amount of bone: Distortion in a panoramic can vary up to 20-25% (All implants are same diameter) Have a two dimensional view unlike CBCT scan which is a 3D view Treatment options for post-extraction sites: 1. Medical risk factors 1. radiation therapy (especially head and neck) 2. diabetes 3. bleeding disorders 4. poor health 5. bisphosphonate use Patient without medical problems (95-98%) vs. controlled diabetic (80-85%-but much lower in an uncontrolled diabetic) Always give a balanced and informed consent to your patient so they know there are risk factors 2. Smoking: Increased risk of unsuccessful osseointegration and also premature loss of implant 3. Dental risk factors: 1.Patient expectations (know this beforehand so you can meet these) 2. Lip line 3.Tissue biotype (want a thick biotype) 4.Shape of adjacent tooth crown 5.Bone level at adjacent teeth 6.Local infection at implant site 7.Restorative status of neighboring teeth (subgingival margins of existing restorations) 8. Width of edentulous space, multiple missing teeth (papilla) 9.Soft tissue and bone defect at implant site 4. Anatomic risk factors: 1. Sinus 2. Blood vessels 3. Nerve What to do: 1.Immediate Implant Placement: get implants placed and restored the same day that you get the extraction Advantages: very quick, reduced overall treatment time & 1 surgical procedure [this can be misleading at times] Disadvantages: morphology of socket may lead to compromised implant position morphology of socket can compromise initial implant stability lack of soft tissue volume for primary closure increased risk of recession complexity of procedure is increased 2.Delayed Implant Placement - with soft tissue healing - with partial bone healing 3.Healed (Late) Placement 4.Alternative Restorations Restorative Options (2.28.2017) Two types of restorations: cement retained and screw retained An impression must be made: Elastomeric or digital Impression copings Scan post/scan body, closed tray, open tray, and lab analogs Traditional impressions: - Patient discomfort - Gaging sensation - Material and logistics cost - Copy of copy more inaccuracies Digital impressions: Advantages: - Higher patient comfort - Easier retakes - Saved logistics and material costs Problems: - Casts still might be necessary Abutment: the structure between the implant and the crown Types: Pre-fabricated & Custom (made custom based on the emergence profile) Sub types Abutments for screw retention Abutments for cement retention (for the purpose of putting crown on top) Angulation: Straight & Angled Abutment selection: A.) Depth of the soft tissue: Vertical height from implant platform to the gingival margin Measured with a periodontal probe A prepable abutment would be preferred B.) Emergence profile: Need a minimum of 3mm from the implant platform to the gingival margin to allow for a gradual transition C.) Angulation (orientation): Ideally, the implant (abutment) should be placed parallel to the long axis of the forces. Small degree of deviation, could be corrected by using custom abutments or pre-angulated pre-fabricated abutments (10°, 15° , 20°). Large degree of deviation Lead to unfavorable forces Less space for restorative material (compromised esthetics) D.) Interocclusal space: Fixed: 7 mm minimum Removable: 12 mm minimum E.) Resistance and retention form: Based on height available Amount of taper Surface area Cement retained: Advantages: Simplicity and familiarity Easier to obtain an esthetic result Fewer porcelain fractures Easier to manipulate in the posterior region Less screw loosening Disadvantages: Difficulty to retrieve (unless a provisional cement is used) Important: Risk of leaving cement subgingivallymay get bone loss, periodontitis, and may lose the implant down the road Implant evaluation is difficult when crowns are cemented If the interocclusal distance is minimal, there will be no resistance or retention from Know the strength and type of cement that you are using Screw retained: Advantages: Easily retrievable Crown will not fall off Low profile of retention No risk of leaving cement behind Disadvantages: Screw loosening Compromised esthetics (there is going to be a hole in the occlusal) Greater chance of porcelain fracture Difficult to access in posterior regions Torqueing: When 2 parts are tightened together by a screw, the unit is called a screw joint. The screw loosens only if outside forces trying to separate the parts are greater than the force keeping them together. Forces attempting to disengage the parts are called joint separating forces The clamping force keeps the parts together. To achieve secure assemblies, screws should be tensioned to produce a clamping force greater than the external force tending to separate the joint. Torque wrench: To tighten a screw, adjust the direction indicator so that the arrow is pointing toward the level arm and rotate clockwise To loosen a screw, adjust the direction indicator so that the arrow is pointing away from the level arm and rotate counterclockwise Implant vs. FPD or Removable Anatomic considerations: Ridge relationship › Attached tissue › Inter-arch clearance › Inferior alveolar nerve › Maxillary sinus › Floor of nose Neighboring dentition: Endodontically treated teeth › Periodontal condition Occlusion Implant restorations (Using Chair-side CEREC) (3.1) Cad/cam fabricated implant-supported hybrid structures for single teeth. the hybrid components are individually milled and bonded to a titanium base. Indications: Hybrid abutments for anterior and posterior single-tooth restorations. Milled custom abutment with cemented crown Hybrid abutment crowns for anterior and posterior restorations. Screw- retained crown Contra-indications: Failure to observe the requirements stipulated by the implant manufacturer for using the selected implant type (diameter and length of the implant must be approved for the respective position in the jaw by the implant manufacturer) Failure to observe the permissible maximum and minimum ceramic wall thicknesses Parafunctions (e.g. bruxism) Use of a luting composite other than Multilink® Hybrid Abutment to lute IPS e.max CAD to the Ti base Intraoral adhesion of the ceramic structures to the Ti base Temporary cementation of the crown on the hybrid abutment All uses not stated as indications are contraindicated. TiBase: titanium base interacting with the fixture or implant (for adhesion to meso-structures) Scan-body: a non-intraoral device to register orientation (added to the Tibase depending on the acquisition system) Scan-post: an impression post which can be used intraorally to digitally capture the position of the implant in relation to the remaining teeth and the soft tissue The implant-specific scan post is screwed together with the implant only for the purpose of optical detection Know the difference between scan-post and Tibase (TQ) Current abutment materials: Titanium and Zirconium (high strength, biocompatible, clinically proven) Zirconium causes internal damage to the implant so use titanium a bit more) IPS e.max CAD Abutment Block Sized to create custom abutments (14) Medium Opacity shades – mimic dentin Cemented to Sirona TiBase (L- large) SRP $307 – refill 5 blocks ($62) IPS e.max CAD Crown Abutment Block Sized to create Screw Retained Crown (16) abutments Low Translucency Shades Cemented to Sirona TiBase (L- large) SRP $360 – refill of 5 blocks ($72) Glazed (prevent biofilm formation) and polished (optimal for gingival adhesion) Peri-implant mucositis: reversible inflammatory process in the soft tissue around functioning implant Peri-implantitis: inflammatory process affecting tissues surrounding functioning implant leads to resorption of the peri-implant bone After we place the implant, monitor the implant Most dentists rely on radiographs and clinical findings to find out whether implants are successful Elastomeric Impressions (3.15) Impressions are usually taken afterosseointegration, soft tissue healing, and development of the emergence profile, so it can be considered when designing the final restoration It can be done with either open or closed tray techniques (elastomeric-polyvinyl siloxane or polyether) For a single implant you can usually get away with doing a closed tray technique (put impression in, wait until it sets, and then take it out like taking an alginate) If you have multiple implants with varying paths of insertion then you should use an open tray technique It can be done with an optical scan (immediate not recommended with the optical blue cam) Need to know: Type manufacturer of implant (Nobel) Tissue level or bone level (level of the osseous crest) Connection type (internal hex, tri-channel, external hex) Size/diameter of the implant (Nobel color codes the implants to make it easier) Position of the implant (path of insertion and number of implants) Impression copings: Impression coping open traystays in impression Impression coping closed traystays in implant Impression coping closed tray (plastic)stays in the impression Open tray technique: make a hole in the tray with the screw sticking out, take an impression and the screw will remain sticking out, then you will have a hole and you will be ready to pour Do not torque the impression copings (only hand tighten them) (TQ) Summary: After healing abutment is removed, the impression coping is placed Make sure impression coping is positioned correctly and inserted completely in the connection Once the impression coping is seated, the manual screw driver is used to fasten the impression coping Only one finger pressure is necessary for tightening, and torque should not be delivered with any type of device for the impression phase A radiograph can be taken to assure full seating of the impression coping into the implant A hole is made in the tray to accommodate the screw, and the impression is made The impression coping is unscrewed from the implant The impression is removed from the patients mouth and the lab analog is attached to the impression coping Closed tray technique: inject around coping and onto the tray, take the impression out, and screw the coping into the impression If you don’t put it in correctly, then your angle is off (look at the grooves and depressions on the coping for proper alignment) Summary: After the healing abutment is removed, the impression coping is placed Make sure the impression coping is positioned correctly and inserted completely in the connection Once the impression coping is seated, the manual screw driver is used to fasten the impression coping Please note that only finger pressure is necessary for tightening and torque should not be delivered with any type of device for the impression phase A radiograph can be taken to assure full seating of the impression coping into the implant The impression is made After the impression material sets, the impression is removed The impression copings is then unscrewed from the implant and is connected to the lab analog The analog/coping assembly is then seated in the impression Live demo: The three protrusions in the coping will match and fully seat within the implant hole Take your driver and tighten the screw that is protruding from the top We will be using PVS today so coat the inside of the tray with adhesive Inject around coping (light body) and then fill up the tray (medium body) and then seat the impression (usually takes 5-7 minutes to fully set) Seat the coping into the assembly and then seat the whole thing into the impression (remember to hand-tighten) Replicate compressibility by injecting around the implant itself in the impression (polyether; the opposite of what you used for the impression so they do not adhere to one another) Pour up the impression using stone to get your cast Implant Assisted Overdenture (3.21) Implant-assisted Prostheses: “Assist" retention and stability Supported primarily by soft tissue and alveolar ridge Implant-supported prostheses: Stability, retention and support are provided from the implant itself or from bars attached to the implants Important facts to know: Attachment retained overdentures provide measurable improved retention and comfort For immediate dentures this is particularly important for preserving bone It is the standard of care that all patients who require full arch extractions be evaluated for & advised of this treatment option Looking at bone loss: 25-30% loss in alveolar ridge height within 1 st year 30% loss in crestal bone width within 1 st year 40-60% continued atrophy over next 3 years Bone loss in the edentulous arch = 6.6 mm in 7 years Bone loss in the dentate arch = 0.8 mm in 7 years Bone loss in the mandibular arch = 4X greater than maxillary arch Note: slow the rate of resorption Evaluation must include: medical, dental history and existing dentition, prosthesis history, existing prosthesis evaluation, a space analysis, patient motivation/desire To insure ideal placement, coordinated treatment with the restorative dentist and the surgeon must occur: radiographs/CT scans, templates, mounted casts, diagnostic wax ups/trial tooth set ups, photographs Rule 1: This is a Prosthetically driven restoration with an Attachment modality The attachments are in addition to all other acceptable requirements for denture retention Key: Plan your prosthesis first then your implant follows Putting in an implant now marries you to the weakest link of the procedure All patients who are getting upper and lower dentures also get a CBCT and implants for free (2 on the mandibular) Possible scenarios: existing prosthesis (acceptable or unacceptable), remaining dentition, hopeless dentition, or no dentition (edentulous and no prosthesis) evaluation of the 5 scenarios will produce variations in the treatment plan The common denominator in all cases is that you must start with an acceptable denture In most cases, we are retrofitting the implant attachments to the (acceptable) denture (VDO, occlusion, occlusal plane, neutral zone/lip and cheek support, esthetics, space available) When retrofittingimportant to have fresh and compatible materials with which to work Rule 2: Space analysis: Vertical space is the distance between the ridge and the occlusal plane Vertical space available is the main constraint Whatever projects above the mucosa must be absorbed by the denture… An acceptable denture allows an accurate Space Analysis A Clinical Remount is the EASIEST way to do a Space Analysis If you are evaluating a recently inserted denture for implant placement Do a space analysis at intermaxillary record or tooth set up Always REQUIRES evaluation at the correct VDO This means: For a Complete Denture – a mounting @ VDO is required For a Partial Denture – if VDO cannot be assured by hand articulation – a mounting is also required Space considerations: Determines the inter-occlusal distance or vertical room necessary for: Denture Tooth ~2mm Denture Base ~2mm Attachment /Patrix (in the denture) ~2mm Implant Abutment (Matrix) ~2mm Implant fixture ~0-2mm For micro ERA attachments: TOTAL 8-10 mm (depending on the attachment system) For Locator attachments: TOTAL 11 + mm (depending on the attachment system) Hopeless dentition: It always starts with…Fabricate immediate/interim denture Space Analysis and Retro-fit Summary: space analysis needs: a.) representation of occlusal plane 2.) representation of the residual ridge Looking at templates/surgical guides: can be diagnostic/radiographic or surgical Diagnostic/radiographic template: Is a clear duplicate of an acceptable denture or a diagnostic wax up, fitted with: Gutta percha or Stainless steels markers Allows for evaluation of bone: CBCT Scan – 3D evaluation (usually use this) Panoramic – Vertical height only and Not an acceptable dx too Denture duplicated in clear acrylic Markers placed in areas most desirable for implant fixtures Most common areas (lower)for 2 implants [lingual to cuspid] & for 4 implants [lateral to 1st premolars] Ideal location based on: a.) inferior alveolar nerve b.) remaining bone c.) size and shape of arch Tooth loss typically leaves mandibular anteriors as terminal dentition Most bone in the canine region when selecting sites for implant placement Note: straight line placement, if possible & Minimumun 10-11mm apart Ideally ~ 15mm Due to destructive rational forces: Should be perpendicular to the midline (don’t want access of rotation to be asymmetrical which could happen if they are not perfectly perpendicular) Do not have an anterior cantilever (don’t want them on an arch) During denture fabricationdetermine canine position and transfer it to the cast Cuspids are marked as preferred area for evaluation with template by CBCT Duplicate denture: If the patient has an acceptable existing denture, then we will only need to duplicate this denture Arrange with the lab, in advance, to borrow the patient’s denture The denture is embedded in this special duplicating flask with alginate on both sides, registering both the polished and intaglio sides. When the denture is removed, the space left by the denture can now be filled with clear ortho resin and a clear duplicate of the denture will be created. Steps: 1. Impress both sides of denture 2. Remove denture and fill with clear acrylic 3. Process in pressure cooker @ 20 lb for 20 min The template is worn during the CT scan The markers show up in one or more segments Surgical template: In most cases the diagnostic template may be modified for surgical use by: removal of the radiographic markers placement of guide pin holes for fixture positioning The channels remaining after removing the gutta percha markers, will now guide the pilot drill Some doctors prefer to open a wider area for implant placement; using the denture as the boundary for placement Another option to provide access to the surgeon while still maintaining the template Computer assisted surgical guide: predictable, prosthetically driven, reduces chair time, specific sleeves and drilling protocols for numerous implant systems, overall goal (safety of patient) Attachments: Selection: prosthetic expectations, financial capability, Dr.’s personal choice, lab experience, available inter-arch space (number of implants-anatomy of ridge and availability) Classification: Resiliency (Movement between the denture & the abutment) and load distribution characteristics The more the prosthesis is allowed to move, the more forces are transferred to the residual ridge Movement: A.) Vertical: (occluso-gingival): Distributes forces to the residual ridge Provides even loading and support from the ridge B.) A/P rotation: axis of rotation around the most posterior attachment ERA attachment: Black processing male stabilizes the denture White retention male provides resiliency to denture movement Engagement of the attachment only occurs in function (occlusal load and lifting) and NOT when passive. The micro ERA can be used with or without metal housing (provides a little more space which can make up for space needed from another area if you do not use) Locator attachment: Space between nylon male and metal housing allows for vertical resiliency and rotational movement Rotary resilient: Stud (i.e. ERA, locator): Hinge, vertical , rotation (mimics the movement of the denture) Provides 95% load relief to the implant and 95% Tissue/Ridge support The more resilient the attachment, the more you must rely on the ridge and tissue for support Abutments: Indications: Simplest – most frequent application for 2 implant fixtures on mandible (Standard of care) When maximum load relief is needed Multiple implants where 1 has a poor prognosis Shape of arch Position of implants (i.e. too close, too far…) Minimal ridge resorption / Small inter-arch space Angulation of implants and inter-arch space will determine abutment selection: Micro ERA (1 pieice)-smallest overall stud attachment (8-10 mm space needed) (2 piece)-allows for angle correction [angle correction is in the abutment; may be 0 degree to 17 degree correction for each fixture) Locator: 11-12 mm space needed (are all 0 degrees) Angle correction depends on the retention rings rotating in its housing for divergent abutments (up to 40 degree angulation) Bar: custom hader bar or prefab SFI bar (12+ minimum needed) Longevity of retention clips/snaps depends on: Size of arch, type of diet, oral habit, home care (way patient cleanses), angulation of stud/bar attachment, and occlusion Occlusion scheme: Rules: no anterior contact in CR, no incisal guidance, no canine guidance in lateral, CR=CO Occlusal plane=1/2 to 2/3 height RMP No porcelain teeth unless the opposing is fixed (and even then use with caution) Lingual contact occlusion: mandibular central fossa centered to the mandibular ridge Contact centered to the mandibular ridge Flat tooth or semi-anatomical tooth on the mandible and the buccal cusp of the lower tooth has nearly been eliminated to only have one contact Begin with anatomical maxillary posterior teeth (30°-33°) Eliminate the additional lateral impact of the maxillary buccal cusps by reducing the buccal cusp Flatten lower posterior teeth to 0-20° Bilateral Simultaneous contact in all movements How tooth selection affects occlusion: Monoplane delivers less lateral force but is harder to remain in “balance” Anatomical delivers more lateral force but is easier to remain in “balance Lingual Contact Occlusion uses a modified anatomical tooth to reduce lateral force and is easier to remain in “balance Remember, Cusped teeth deliver greater lateral force than Flat teeth Insertion, adjustment and attachment activation: Insertion and Adjustments: Day of Insertion: Fit & insert denture as a conventional * denture, patient remount, adjust where needed Attachment activation: Several weeks/visits (occurs a lot later when patient is comfortable and oral hygiene stable) Adjust where and when needed Reinforce OH Evaluate for attachment activation Attachments are incorporated into denture after occlusal equilibration (clinical remount) and all sore spots have been eliminated Follow-up long term care: Maintenance / Denture with attachments Cleaning instructions: Brush denture before soaking to loosen particles Soak for only 10-15 minutes then rinse and soak overnight in plain water No tablets containing Chlorine Recall: As recommended for natural/implant dentition (3-6 months) Evaluate fixtures attachments and supporting tissues Monitor denture at each recall for residual ridge changes and “fulcruming” (denture will fulcrum and become implant-borne and the weakest link of the system will take over) Care must be taken to keep these prostheses tissue borne Relines/rebases are more frequent than conventional dentures due to differences in bone resorption rates Denture base options: To reinforce denture base: Fiber mesh may be processed into the denture base A framework may be processed into the denture base Does not replace diligent recall and reline Attachment care: Instruct Patient to insert denture with finger pressure only Do not bite into place – the attachments will prematurely wear Attachments are replaced at annual recall – There is a fee associated with this. Patients must be told at initial tx planning. If fixtures are misaligned, attachments may be replaced sooner (q 6-12 months) Common causes of attachment care: Biting the overdenture into place ν Cleaning the abutments with an abrasive cleaner Denture Cleansers – can soften the nylon over time Placement of a nylon attachment with too much retention – excessive wear on metal component Tobacco chewing and smoking ν Using metal that is too soft when casting a plastic pattern Over-shellblasting when de-casting processed denture ν PATH- If the attachments are not within 5° of parallel to each other Path of insertion not consistent with anterior (or posterior) tissue undercuts