Prosthodontics 2nd committee PDF

In red → Important! Haneen Ali Prosthodontics– 2nd committee 1st lecture: History and components of implants (Dt Burcu): ­ Branemark → Swedish orthopedic professor ­ 1952 → during his research, he observed revasculari...

In red → Important! Haneen Ali Prosthodontics– 2nd committee 1st lecture: History and components of implants (Dt Burcu): ­ Branemark → Swedish orthopedic professor ­ 1952 → during his research, he observed revascularization in the rabbit’s fibula through light microscope ­ Osseointegration: o Direct contact between the bone surface and the implant was established o In 1965, the first dental implant was placed in an edentulous patient ­ Types of dental implants: ­ Indications for implant: ­ Contraindications: o Tooth loss o Uncontrolled systemic disorders o Congenital tooth absence o Psychiatric disorders o Poor oral muscle coordination o Radiation therapy o Discomfort from removable dentures o Smoking o Poor oral hygiene ­ Applications: o Single tooth o Partial/complete edentulism o Maxillofacial prosthetics o Craniofacial prosthetics ­ Implant components: o Crown, abutment, abutment screw, implant body o Implant body: ▪ Titanium screw-shaped ▪ Hydroxyapatite-coated screw-shaped ▪ Titanium plasma-sprayed cylinder ▪ Hydroxyapatite-coated cylinder o Types of implant bodies: ▪ Smooth, machined, textured, coated o Types of abutments: ▪ Stock abutment, tissue level, straight, angled, bone level, custom abutment, milled abutment, UCLA abutment, locator abutment, screw-retained, cemented abutment, temporary abutment o In implant restorations, the tissue level is closely related to the implant platform o Bone-level restorations are closely related to the abutment platform ▪ The abutment is typically a platform-switch type (esp. in anterior teeth) ­ 1) Temporary abutments o Impression abutments o Healing abutments o Metal or plastic temporary abutments  Haneen Ali ­ 2) Permanent abutments o A) Material used: titanium, zirconia o B) Manufacturing method: stock abutment, custom abutment, (UCLA) o Stock abutment → straight angled o Titanium abutments, zirconia abutments o UCLA abutment (permanent, expensive custom, inside part made out of gold) o C) Retention method of superstructure: screw-retained abutment, cement-retained abutments o Screw-retained abutments: o Advantages: o Disadvantages: ▪ Easy to remove ▪ Aesthetic ▪ Solves retention issues ▪ Ideal occlusal morphology ▪ No cement issues ▪ Difficult passive fit control ▪ Difficult to work with ▪ Risk of porcelain fracture: in teeth with narrow occlusal tables, and if the screw is close to the occlusal margin → risk of porcelain fracture (related to the screw exit site and occlusion) o Cement-retained abutments: o Advantages: ▪ Occlusal load and anatomical profile: Even if not positioned ideally → can achieve occlusal load and an anatomical emergence profile ▪ Easier passive fit: Space provided by cement allows for easier passive fit ▪ Resistance to screw loosening: Increased resistance to screw loosening and fracture ▪ Easier occlusal alignment: Achieving optimal occlusal alignment is often easier o Disadvantages: ▪ Prosthesis may need to be cut and removed if problems arise ▪ Cement residue ▪ Distance of 7 mm (4mm crown, 3mm biological width) is required between the implant and the opposing tooth for proper retention ­ Implant-abutment connection configuration: o External and internal connection o Disadvantages of external connection: ▪ Screw loosening ▪ Rotational incompatibilities ▪ Aesthetic ▪ Microbial seal (lateral movement) ▪ Implant abutment (İnterface- Microgap -Bacteria) o Advantages of internal connection: ▪ Less screw loosening ▪ Better aesthetic ▪ Improved microbial sealing ▪ Better connection strength ▪ More platform switch options In red → Important! Haneen Ali o Disadvantages of internal connection: ▪ The weak link is not the screw, but the bone ▪ The lateral walls of the implant can become thinner at the junction area (for internal hexagon) o Conical connections: morse taper and cone screw o Advantages of Morse taper and platform switching applications: ▪ Microgap reduced ▪ Less bone loss when placed supracrestally ▪ Marginal bone resorption is decreased ▪ Biological width formation occurs apically and laterally at the abutment and implant platform ▪ The thickness of soft tissue increases due to the abutment diameter being smaller than the implant diameter ▪ The design reduces micromovements on the implant during the distribution of occlusal force o Cone screw: ▪ Internal, conical, self-locking connection ▪ Utilizes the self-locking principles of the Morse taper, with a screw used to connect the abutment to the implant ▪ All cone screw connections also provide the advantages of platform switching applications o In Morse taper connections, the difference in taper angle (a, b) and contact length (c, d) is significant ▪ A connection with a smaller angle (b) can impact the stability of the connection compared to a larger angle (a) ▪ Similarly, a connection with a longer contact length (d) can affect stability compared to a shorter contact length (c) o Friction-fit: ▪ The internal hexagonal connection is shaped like an inner hexagon ▪ Possesses anti-rotational features. ▪ The friction fit connection is created by the friction between the abutment's conical connection and the internal surface of the implant connection ▪ Since the abutment is fully engaged with the implant's internal hexagon, this connection is referred to → friction fit o Slip-fit: ▪ There is a passive seating fit between the two connection components (implant and abutment) ▪ The internal cylindrical hexagon is categorized into three separate groups: spline, cam tube (tube-in- tube), and tri-channel (tri-lobe) o Butt-joint connections:  Haneen Ali o Platform switching: ▪ Emerged from studies conducted in 1991, which demonstrated minimal or no bone resorption when using narrow prosthetic components of 4.0 mm width on implants of 5.0 mm width ▪ Platform switching has been available in the market since the introduction of cone screw and Morse taper implant designs by companies such as Straumann, Ankylos, Bicon, and Astra ▪ These conical designs inherently possess the feature of platform switching ▪ It has been reported that the medial positioning of the implant-abutment connection allows for the horizontal formation of biological width, thereby gaining additional space for soft tissue attachment ▪ This means that less bone loss is required to compensate for the biological width ▪ Platform switching is a method to prevent crestal bone loss ▪ Used more in internal connections ▪ In traditional applications, the diameters of the implant and abutment are equal, whereas in the platform switching concept, the diameter of the abutment is narrower than that of the implant ▪ For example, a 5 mm diameter implant can be used with a 4 mm diameter abutment ▪ Advantages: (translated from Turkish so not sure how accurate) The infiltrated inflammatory cells around the implant-abutment connection get trapped in the angular form of the interface → prevents their apical spread The horizontal width of the platform provides additional space for the biological attachment to establish. The impact of the microgap between the implant and abutment on bone resorption can be minimized o Three major implant abutment connections: (a) interface-free (tissue-level or single-piece implants), (b) butt-joint, and (c) platform-switch. (Ab = abutment) 2nd lecture: Stress in dental implants (Dt. Burcu): ­ Biomechanical stress is an important risk factor in implant dentistry ­ Its magnitude is directly related to the applied force ­ Patient force factors: o Parafunction: bruxism, teeth clenching, tongue thrusting/suction o Crown height space o Chewing dynamics o Arch position o Opposing arch position ­ Parafunction: o Characterized by repeated or sustained occlusion → harmful to the stomatognathic system o Most damaging when applied to implant prostheses o Most common cause of both early and late implant failure o Local factors: tooth shapes, occlusion, soft tissue changes o Systemic factors: cerebral palsy, epilepsy, drug-induced dyskinesia, neurological, psychological In red → Important! Haneen Ali ­ Bruxism: o Signs: ▪ Increase in the size of the temporal and masseter muscles ▪ Deviation of the lower jaw from the straight opening path during opening ▪ Restriction of mouth opening ▪ Increased mobility of the teeth ▪ Cervical abfraction in the teeth ▪ Fractures in teeth or restorations ▪ Descementation o Classified as absent, mild, moderate, or severe o When anterior teeth are worn, they often show eruption ▪ In this case, alveolar bone reduction and crown lengthening procedures will be necessary o When there is a decrease in vertical dimension → crown lengthening in the anterior region is not required o In severe cases of bruxism, restoration of the occlusal plane, anterior incisal guidance, or both may be necessary o Fatigue fractures: ▪ A force so large that a single cycle can cause a fracture ▪ Even a lower magnitude force, when applied repetitively to an object → leads to a fracture ▪ As muscles strengthen, the magnitude of the forces generated increases, and the number of load cycles experienced by prosthetic components also increases o Occlusal guards: ▪ Premature or posterior contacts during eccentric movements increase stress conditions ▪ Eliminating eccentric movements leads to improvements in PL health and muscle activity within 1 to 4 weeks ▪ In partially edentulous patients, a maxillary TMD splint can be designed with relief features over the crowns corresponding to the implants Allowing the entire load to be carried by the teeth ▪ In a complete arch implant-supported prosthesis → maxillary splint can be used to remove the occlusion from the mandibular posterior cantilever ▪ Sudden forces on a maxillary posterior unilateral implant-supported fixed restoration in occlusion with mandibular teeth can also be reduced by using a soft-liner material ▪ If there are opposing complete arch implant-supported restorations → splint is designed so that there is only anterior contact during centric occlusion and mandibular movements o Treatment plan: ▪ Use of additional implants with larger diameters to reduce the risk of excessive loading ▪ By modifying the anterior teeth and creating a new compatible anterior guidance → posterior interferences can be avoided during lateral movements ▪ Since lateral forces significantly increase the stress at the implant-bone interface → remove posterior contacts → reduces the destructive effects of angular forces during bruxism ▪ During lateral movements, the presence of posterior contacts causes almost all fibers of the masseter, temporalis, and external pterygoid muscles to contract, resulting in greater forces being applied to the anterior teeth/implants ­ Teeth grinding: o Habit causing constant force to be applied to opposing occlusal surface without lateral movement of an occlusal surface o Forces generated during teeth grinding develop at a steeper angle to the occlusal plane, at least in the posterior regions of the mouth o Increase in the mobility of the teeth → force that exceeds physiological limits, bone loss, and the coexistence of these factors o This situation requires a further examination from a parafunctional perspective and is very important if the placement of an implant in the mobile tooth area is being considered  Haneen Ali o Fremitus o Cervical abfraction o Common clinical finding: presence of grooves on lateral borders of tongue that follow the cervical contours of teeth o Fatigue fractures: ▪ When continuous force is not eliminated or at least reduced in intensity or duration →fractures can be observed in the restoration ▪ This condition can also occur in the bone, resulting in implant mobility and failure o Treatment plan: ▪ Similar to bruxism’s treatment plan ▪ Vertical forces are less destructive than horizontal forces ▪ Changing the anterior occlusal scheme is not as critical as in bruxism patients ▪ Splint use ▪ (Anterior teeth withstand vertical forces, while posterior teeth withstand horizontal forces) ▪ A common reason for implant failure during the healing period is parafunction associated with the use of a soft tissue-supported prosthesis on an implant embedded in bone ▪ Soft tissue becomes compressed ▪ Micro-movement occurs in the implant body ▪ Inadequate osteointegration o Prosthetic evaluation: ▪ Anterior implants exposed to parafunctional forces in the lateral direction should undergo further treatment evaluation ▪ Wide-diameter implants ▪ If healthy natural canines are present → canine guidance is provided during lateral movements ▪ If there are implants in the canine position or if the absence of canines has been compensated with a bridge → additional implants are placed to distribute the force, and a mutually protective occlusion is established ▪ Centric vertical contacts should be designed to distribute stress along the long axis of the implant ▪ Creating narrow occlusal surfaces and reducing occlusal forces helps to minimize unwanted lateral forces ▪ Enamelplasty (cutting part of the enamel) ­ Tongue thrusting and sucking: o The application of unnatural forces by the tongue on the teeth during swallowing o Forces generated during tongue sucking are of lower intensity compared to other parafunctional forces and are inherently horizontal in nature ▪ This can increase stress in the perimucosal region of the implant o Single-state surgery o Full upper denture-lower Kennedy I o In a patient with a lateral tongue thrust habit, after the placement of mandibular implants, complaints may arise that there is not enough space for the tongue o Even in the absence of tongue sucking, the tongue adapts to the existing space, and its dimensions may increase along with tooth loss In red → Important! Haneen Ali ­ Crown height distance: o Defined as the distance from the bone ridge to the occlusal plane in the posterior region and from the bone ridge to the incisal edge in the anterior region o The ideal → 8 and 12 mm o Movable prostheses often exhibit a CHM greater than 12 mm due to the resistance of artificial teeth and acrylic bases, as well as the presence of retainers, bars, and oral hygiene considerations o When the crown height distance increases, methods to reduce stress should be implemented: ▪ Increase the number, sizes, and surface area of implants based on design and implant length. ▪ Connect the implants to each other ▪ Create movable restorations ▪ Provide additional soft tissue support for overdenture prostheses o Both restricted and excessive CHD can lead to an increase in prosthetic issues o Excessive crown height distance can increase all mechanical complications associated with implant prosthetics due to the increased amount of force o Crown height distance - Lateral forces o Angled load - Maxillary anterior o Stress reduction methods: ▪ Reducing the length of the cantilever ▪ Decreasing offset forces in the buccal and lingual directions ▪ Increasing number of implants ▪ Increasing diameter of the implants ▪ Designing implants to increase their surface areas ▪ Creating less mobile restorations with reduced retention and obtaining support from soft tissues ▪ Removing movable restorations during sleep hours to reduce the destructive effects of nocturnal parafunction ▪ Splinting implants that support fixed or removable prostheses ­ Masticatory dynamics: o Amount of forces affecting the implant system is determined by the dynamics of the masticatory muscles o The patient's size, gender, age, skeletal condition, dental status, and duration of edentulism (muscle atrophy), as well as diet, influence muscle strength, masticatory dynamics, and maximum biting force o When there is an increase in the dynamics of the masticatory muscles, other force magnifying factors should be reduced ­ Arch position: o Maximum biting force is greater in the molar region and decreases as it moves anteriorly o Biting force of anterior teeth decreases in the absence of posterior tooth contacts and is greater when there are posterior occlusions and eccentric contacts o When the posterior teeth are not in contact → two-thirds of the fibers of the temporalis and masseter muscles do not engage → decrease in biting force o When teeth are lost, the bone density in edentulous areas varies across different regions of the mouth o Posterior regions→ develop less dense bone compared to the anterior regions o The arch position at the greatest risk is the posterior maxilla o Followed by the posterior mandible and anterior maxilla ­ Opposing arch: o Natural teeth transmit greater forces through occlusal contacts compared to soft tissue-supported complete dentures o A completely implant-supported fixed prosthesis cannot benefit from the proprioception present in natural teeth, and patients can bite with forces up to four times greater than with natural teeth o When there is a complete denture on the opposing arch, the biting force is lower compared to an implant- supported prosthesis o Natural teeth instead of a complete denture on the opposing arch → biting force will increase  Haneen Ali o Cantilever length should be reduced, or the number of implants should be increased o In cases where there are fixed restorations over implants in both jaws → decrease in proprioception in the patient, leading to greater forces during parafunction o Especially if the crown height is significant, the cantilever should be reduced ­ Summary: o Patient strength factors can vary significantly between individuals o Treatment plans are adjusted based on the specific strength factors of each patient 3rd lecture: Singe-tooth implant (Dt Burcu): ­ Reasons for maxillary anterior single tooth loss: o Agenesis: failure of tooth development during the embryonic stage o Trauma o Endodontic Failure o Fractures: breaks in the tooth structure that may necessitate extraction o Resorption: loss of tooth structure, often due to external factors o Caries: tooth decay that can lead to the loss of a tooth ­ Maxillary anterior single tooth replacement options include: o Classic Fixed Prosthesis → fixed dental bridge anchored to adjacent teeth o Missing of lateral incisor, fixed prosthesis for lateral incisor loss o Removable Partial Denture (RPD) o Resin-bonded fixed prosthesis o Implant-supported crown ­ Every vertical bone loss usually leads to soft tissue retraction → negative impact aesthetically in all edentulous areas and neighbouring teeth ­ Advantages of fixed partial dentures (FPDs): o Patient compliance and patient anxiety o Consequences of failure o Financial implications o Mobility of adjacent teeth o Tooth volume and position ­ Adjacent teeth in the anterior implant region should ideally show minimal mobility ­ When there is moderate or excessive parafunction → mobility of adjacent teeth poses a significant risk ­ Inadequate bone height, width, or insufficient inter-dental space → contraindication for implants ­ If the space between the lateral incisors is less than 5 mm → consider a cantilever fixed partial denture (FPD) attached to the canine o Or orthodontic → if not enough space to place an implant ­ Resin-bonded prostheses are temporary restorations applied during bone grafting and soft tissue grafting prior to implant placement ­ Contraindications for resin-bonded prostheses: o Thin enamel on adjacent teeth → etching can be harmful o Mobility of adjacent teeth o Vertical overlap o Bruxism o Anterior diastema o Short clinical crown o Malocclusion In red → Important! Haneen Ali ­ Factors in maxillary anterior single tooth replacement: o Patient compliance and anxiety o Patient request/reference o Treatment duration o Consequences of failure to damage adjacent teeth o Cost o Aesthetic o Patient age o Mobility of adjacent teeth o Crown height and occlusal relationship o Mesiodistal space at crown and bone levels o Available bone height o Available bone width (buccolingual) o Type of soft tissue coverage o Temporary prostheses ­ Implant dimensions: o Most dental implants typically have a diameter of 5 mm or less and are circular in cross- section ­ Natural maxillary anterior crown size: o Cervical width of a natural maxillary anterior crown ranges from 4.5 to 7.0 mm o Never perfectly circular ­ Tooth dimensions: o For central incisors and canines, the faciolingual dimension at the cervical area is often larger than the mesiodistal dimension ­ Cingulum ­ Mesio-distally: o İf the implant is placed closer than 1.5 mm to the adjacent tooth → complications such as microgap formation, biological width violation, or stress-related bone loss o This can result in bone loss around both the implant and the adjacent tooth o Such issues negatively impact interproximal aesthetics and the sulcular health of both the implant and natural teeth o Dental roots-orthodontic treatment used if not enough space ­ Bone-height: o Aesthetic zone implants require careful attention to several factors, with crestal bone height being one of the most critical criteria o The ideal central crestal position of the implant should be located 2 mm below the facial enamel- cementum junction of the adjacent teeth o Ideally, the interproximal bone should be angled such that it remains 3 mm below the central crestal position o Increasing bone height through grafting → more challenging and less successful compared to augmenting width with grafts placed in extraction sockets or for ridge expansion o Orthodontic extrusion ­ Faciopalatal width: o Before an anterior tooth extraction, the initial bone loss often occurs in the facial bone o After the tooth is extracted → bone first loses width and then begins to lose heigh o Faciolingual bone width should be at least 3 mm greater than the diameter of the implant to ensure proper stability and integration o Bone augmentation procedures aimed at increasing width are typically very successful, improving both aesthetic and functional outcomes  Haneen Ali ­ Soft tissue: o Tooth is lost → interseptal bone is lost → bone remodels toward the facial bone plate which is positioned more apically than the palatal bone o Result of this → interdental papilla may become depressed o Height of papilla influenced by absence of interdental contact (know highlighted parts) ­ Implant crest module planning: ­ Implant size: o Mesiodistal size of missing tooth o Distance to adjacent tooth roots o The ideal width of single-tooth implants should match the width 2 mm below the enamel-cement junction of the adjacent natural tooth o There should be 1.5 mm between the implant and adjacent teeth o At least 1.5 mm of bone must be present facially, plus the size of the implant, and an additional 1 mm of palatal bone o If the distance between the interseptal bone and interproximal contact is 5 mm or less → it will fill the papillary space ­ Screw retention and Cement retention: ­ Advantages of cemented restoration: o Aesthetic o Passive fit o Decreased laboratory technique precision ­ Peri-implantitis? o Inflammatory process affecting soft and hard tissues surrounding implants o In cemented restorations, the cleanliness of the cement is importance ­ Indications for screw-retained restorations: o Simplicity in removal: they do not require complex treatment procedures for removal, making them more convenient for adjustments or repairs o Establishing gingival emergence profile: they can effectively establish the gingival emergence profile, ensuring a natural aesthetic outcome o Insufficient interocclusal space: particularly useful in cases of inadequate interocclusal space (minimum of 4 mm), where traditional cement-retained options may not be feasible ­ Complications: o Screw-loosening ▪ Abutment screw loosening more commonly observed in screw retained compared to cement retained ­ Titanium-based implants: cement, recycling ­ Occlusal adjustment (Stage 1): o When patient bites down on paper in a light way → paper should be able to be removed from between teeth o Make sure forces from biting is evenly distributed ­ Occlusal adjustment (Stage 2): o We ask patient to bite hard in centric occlusion → so teeth moves bit apically In red → Important! Haneen Ali 4th lecture: Single-tooth replacement treatment options (Dt. Burcu): ­ The maxilla distributes force, while the mandible absorbs force ­ Pathological overload is reached at 3000 micrograms ­ Elastic modulus: o Defines the amount of strain (the ratio of the change in dimension to the original dimension) that occurs under a specific stress, which is directly related to bone density ­ Mish classification of bone density: o D1: dense cortical bone ▪ Anterior mandible ▪ Thick compact bone ▪ Not favourable for implant o D2: porous cortical bone with coarse trabecular bone ▪ Anterior maxilla, posterior mandible o D3: porous cortical bone with fine and weak trabecular bone ▪ Posterior maxilla, posterior mandible ▪ Thinner cortical layer with lower density o D4: fine trabecular bone ▪ Posterior maxilla ▪ Very thin, low-density ▪ Not favourable for implant ­ Bone strength varies according to bone density ­ Bone density affects the elastic modulus of the bone ­ Differences in bone density influence the implant-bone contact ratio ­ Variations in bone density alter the stress/strain distribution at the implant-bone interface ­ Alternative options for single tooth replacement: o Removable partial dentures, resin-bonded bridges, space maintainers, fixed partial denture, implant- supported prosthesis ­ Removable partial dentures: o Indicated for the replacement of three or more posterior edentulous areas, or for the loss of a canine and two or more adjacent teeth o Patient rarely accepts an FPD to compensate for the loss of a single posterior tooth in the long term o Disadvantages: ▪ Requires opposing arch stabilization due to its large mass ▪ Food debris and plaque accumulation ▪ Issues due to mobility ▪ Speech difficulties ▪ Chewing problems ▪ Lack of clinical evidence ▪ Bone loss ▪ Loss of supporting teeth ­ Resin-bonded bridges: o In the restoration of single tooth losses limited to natural teeth in the posterior region → resin-bonded fixed partial dentures are the second option o Minimal preparation requirements on adjacent supporting teeth o Low cost o Good treatment option if skeletal growth is not complete o In young patients → absence of the need for a crown and the reduced risk of damaging the pulp are additional benefits  Haneen Ali o Most successful in maxillary anterior region (then mandibular anterior, maxillary posteriors and mandibular posteriors) o Debonding of resin often occurs during function o Due to high cement failure rates → should be considered temporary restorations ­ Fixed partial dentures: o Most used for compensating for single posterior tooth losses → three-unit fixed restoration o Advantages: ▪ Most common treatment ▪ Time restores function, aesthetic and intraoral health ▪ Long-term presence in mouth has been proven ▪ Mesiodistal space is less than 6 mm ▪ Potential mobility development in supporting teeth benefits from splinting ▪ Patient compliance is high, and fear is low ▪ When unsuccessful, the consequences are not severe o Disadvantages: ▪ Most common complications are caries and endodontic failures in supporting teeth ▪ Increased plaque retention on the bridge body raises the risk of caries and periodontal disease ▪ It can harm healthy teeth ▪ Prosthesis fails with the loss of supporting teeth ▪ Fractures ▪ Aesthetic concerns ▪ Cement failure of the restoration o Contraindications: ▪ Weak support from the abutment teeth ▪ Insufficient hard and/or soft tissue in aesthetic areas (contour of the bridge body) ▪ Patient may not permit preparation of the supporting teeth ▪ Wide pulp horns in clinical crowns (in young patients) ­ Single tooth implant: o Best option for compensating for a single posterior tooth loss is generally a single tooth implant o Advantages: ▪ No need for splinted restorations on adjacent teeth (lower risk of caries, endodontic treatment, porcelain fracture, tooth fracture, and dislodgement of restorations) ▪ Psychological benefits ▪ Hygiene ▪ Reduced sensitivity in the teeth ▪ Enhanced aesthetics ▪ Preservation of bone ▪ Decreased risk of adjacent tooth loss o Healthy posterior teeth can move vertically by 28 micrometres o Lateral movements being less than 75 micrometres o The presence of adjacent teeth with increased clinical mobility is a contraindication for implants o Indications for posterior 3-unit FDP in presence of contraindications for posterior single tooth implants: ▪ Insufficient bone volume ▪ Moderate to advanced mobility in 2-4 adjacent teeth ▪ Limited time for patient treatment In red → Important! Haneen Ali ­ Temporary selections: o In aesthetic areas, RPD are frequently used as interim (temporary) prostheses during the implant healing period o When tooth replacements are needed in the aesthetic zone → resin-bonded prostheses can be created to protect the area and provide a more functional temporary prosthesis o Short clinical crown-occlusal relationships o Soft tissue-bone augmentation ­ Implant selection: o Most common problem → loosening of abutment screw o Implants should have anti-rotational features o Ideal diameter for single-tooth implants is determined by mesiodistal size of lost teeth ▪ And the buccolingual size of area where implant will be placed o Ideal implant diameter: ▪ 1.5 mm away from adjacent teeth ▪ 1.8 mm away from lateral width of edentulous ridge ▪ 3 mm narrower than MD size of tooth ▪ 3 mm narrower than the BL dimension of bone o Premolar implant replacement: ▪ Most ideal posterior teeth to be displaced with an implant are the first premolars in both jaws ▪ The need for bone grafting is often seen before maxillary premolar implants ▪ Maxillary canine has an 11-degree angle o First molar implant replacement: ▪ Most frequently lost teeth in posterior segment ▪ MD size ranges from 8-12 mm ▪ Increased surface area → enhances implant’s resistance to component fractures → improves abutment stability and optimizes the emergence profile of crown ▪ If a tooth that is 12 mm is displaced with an implant that has a diameter of 4 mm, it will create a cantilever of 4-5 mm at the marginal ridge of the crown (not good) ▪ When the MD size of the missing tooth is 8-12 mm, an implant with a diameter of 5-6 mm is recommended If the mesiodistal size is 14 mm or greater, two implants with a diameter of 4 mm should be considered Bone stimulation ▪ When MD space is 12-14 mm → enamelplasty and orthodontic treatment 5th lecture: Implant treatment plan choices (Dt. Burcu): ­ Don’t forget to pay attention to aesthetic criteria, lip support, smile line and interocclusal distance ­ Classification of implant-supported dentures: o Fixed prostheses: FP-1, FP-2, FP-3 o Removable prostheses: RP-4, RP-5 ­ Fixed prostheses FP-1: o Only replace anatomical crowns in areas where teeth are missing → resembling appearance of natural teeth o Fabrication of FP-1 is indicated in: ▪ Minimal loss of soft and hard tissues and the implants can be ideally positioned o Replaces only the crown → looks like a natural tooth  Haneen Ali ­ Fixed prostheses FP-2: o Replace a portion of the anatomical crown and root o Indicated in: ▪ Cases where bone resorption does not allow for the creation of an FP-1 prosthesis with a natural tooth appearance ▪ Especially when there is a more apical implant placement o In these prostheses, while the incisal one-third is positioned correctly, the gingival one-third is located more apically → resulting in a prosthetic appearance with a longer clinical crown length o Consequently, this may raise aesthetic concerns in the aesthetic zone depending on the patient's smile line o Replaces crown and a portion of root → crown contour appears normal in occlusal half but elongated or hypercontoured in gingival half ­ Fixed prostheses FP-3: o Also replace the surrounding soft tissues along with the missing teeth o In these prostheses, areas that are prone to rapid resorption, such as the interdental papilla region, are restored with pink restorative materials (such as porcelain, acrylic, etc.) o SP-3 prostheses should be preferred, especially in cases with advanced bone resorption, to meet aesthetic needs as well o Replaces missing crowns and gingival color and portion of edentulous site → acrylic gingiva might be used ­ RP-4: o Removable prosthesis o Overdenture supported completely by implant o Retention achieved using bars and clips o For the fabrication of HP-4 removable prostheses, a greater vertical distance is required compared to fixed prostheses o Implant positions should be located more lingually and apically ­ RP-5: o Removable prosthesis o Overdenture supported by both soft tissue and implant o Number of implants varies depending on the tissue from which support is sought o Advantage of RP-5 prostheses → require fewer implants compared to fixed prostheses, making them more economical ­ Implant supported overdenture prostheses: o Implant and/or tissue-supported overdenture prostheses can be categorized into five groups based on the types of attachments they include: ▪ Telescopic prostheses (not used) ▪ Ball attachment prostheses ▪ Bar attachment prostheses ▪ Magnetic retention prostheses ▪ Locator attachment system (most used) In red → Important! Haneen Ali 6th lecture: Implant key positions and treatment plan based on number of implants: (Dt. Burcu) ­ Ideal implant treatment: o Short duration, affordable, fewer operations, increased comfort, more acceptable, fewer complications o 50% mandibular posterior less than 6 mm o 40% maxillary posterior less than 6 mm o Cantilevers must withstand posterior chewing forces ­ Logic of treatment planning: o 98% pre-loading surgical success o Post-loading failure rate is 3-6 times higher o The failure rate in soft bone regions shorter than 10mm is 15% ­ Biomechanical factors: o Excessive stress transmission o Male o Bruxism o Opposing implant-supported o Group function occlusion ­ Mechanical complications: o Abutment screw loosening o Uncemented prosthesis o Porcelain fracture ­ Implant bone composition: o Stress accumulation in crestal bone o Bone loss and bacteria o Peri-implantitis ­ Treatment costs and economics: o In posterior maxillary region, 2 scenarios: ▪ 1) Sinus lifting healing and 3 implants ▪ 2) Two implants and cantilever ▪ Cantilever accumulates a lot of stress on anterior implant ▪ Pricewise → 1st scenario cheaper (2 times than 2nd scenario) ▪ But 2nd scenario is more successful ­ Expectation of treatment repetition: o Biomechanical complications arise in the early stages o The patient expects a repeat of the treatment ­ Misch’s treatment planning: o 1) Prosthesis design o 2) Patient force factors o 3) Bone density in edentulous areas o 4) Key implant positions o 5) Implant diameter o 6) Implant size o 7) Available bone in edentulous areas o 8) Implant design ­ Implant or bridge? o İn splinted fixed prostheses → 22% risk of caries formation within the first 10 years o 15% risk of experiencing on endodontic problem o No risk of caries in implants  Haneen Ali ­ Implant-tooth connection: o Teeth move 28 microns apically o 56-108 microns in the horizontal plane o When implant → no PDL connected to bone → moves 5 times more than natural tooth o Cantilever effect: stresses and forces experienced by dental implants when prosthetic teeth are only supported by one end ­ Implant position: o Tooth-implant interface 1.5 mm o 3 mm gap should be left between implant-implant → ­ Key points of implants: o Avoiding cantilever o Three potics are absent o Rule for canine and first molar (placement) o Arch dynamic ­ If no cantilever: o Force X lever arm o Dislocating and destructive effect ­ Tooth loss and amount of implants: o 1-2 adjacent tooth loss → one implant for each tooth o 3-4 adjacent tooth loss → two terminal abutments o 5-14 adjacent tooth loss → two terminal abutments with additional pier abutments ­ When deciding on a cantilever → actors such as parafunction, crown height, chewing dynamics, implant placements, and opposing arch should be carefully examined ­ The cantilever should not be longer than the A-P distance ­ If the force factors are not suitable, the cantilever length should be reduced, the number of implants increased, or the surface area related to the implant design should be enlarged ­ A posterior cantilever longer than 2 pontics is not indicated ­ Arch shape affects the A-P distance: o Square arch form → 2-5 mm A-P distance o Ovoid arch form → 6-8 mm A-P distance o Tapered arch form → larger than 8 mm A-P distance o A-P line: draw an imaginary line from last posterior implant and from the most anterior implant ­ Single tooth loss: o Should be centered in the mesiodistal (M-D) direction o Implant diameter + 3 mm = minimum gap o Cantilever effect ­ Two tooth loss: o If sufficient space → at least 2 implants should be placed (for the interdental papilla) o Sufficient space: ▪ Depends on diameter to be used if distance is less than 12 mm → cantilever ­ Three tooth loss: o 2 terminal implants → ideal o Cantilever class 1 lever effect ­ Four or more tooth loss: o Terminal key teeth position o Third implant usually necessary o Especially at canine and molar tooth regions In red → Important! Haneen Ali ­ Cantilever option: o Used in edentulous mouth o Maxilla more stable in function o Mandible moves buccally and lingually at the edges o In case of cantilever: use more implants, wider diameter and cantilever length should be reduces ­ Preventing placement of three pontics: (not important) o Bending and tensile forces in metal o Stress-absorbing o Maximum gap for 2 premolars is 13.5-16 mm o One molar is 10-14 mm o One molar + one premolar gap = three tooth loss o Invalid in lower anterior region ­ Canine and first molar rule: o Placing an implant for canine loss is the ideal prosthetic option o A fixed restoration addressing the loss of the canine and two or more adjacent teeth should not be performed ▪ Implant-supported fixed restoration should be considered o Loss of three adjacent teeth o Lateral direction of force in mandibular movements increases stress o Magnitude of biting force in the canine region compared to the anterior area o A) When the central, lateral, canine, and first premolar are missing: ▪ Ideal key implant positions are the central and first premolar (Rule 1, no cantilever) and the canine position (Rule 3, the canine and first molar position) o B) When the central, lateral, canine, first premolar, second premolar, and first molar are missing: ▪ The three key implant positions are the central and first molar sites (Rule 1), and the canine site (Rules 2 and 3, no three adjacent pontic and canine and first molar position) o C) When the central, central, lateral, canine, first premolar, and second premolar are missing: ▪ There are three key implant positions: the central and second premolar (Rule 1, no cantilever) and the canine position (Rule 3, the canine and first molar position) o D) When eight adjacent teeth are missing from second premolar to the opposite canine: ▪ There are four key implant positions: canine and second premolar position (Rule 1), the opposite canine (Rule 3), and one of the central incisor positions (Rule 2) o E) When 10 adjacent teeth are missing from second premolar to second premolar: ▪ There are 5 key implant positions: the 2 second premolar sites (Rule 1), the 2 canine sites (Rule 3), and one of the central incisor positions (Rule 2)  Haneen Ali o The 1st molar is also a key implant position when 3 adjacent posterior teeth are missing o Bite force doubles in the molar position compared with the premolar position in both the maxilla and mandible o When 3 or more adjacent teeth are missing, including a 1st molar, the key implant positions include the terminal abutments and the 1st molar position ­ Arch position rule: o Teeth are divided into segments according to their inherent biomechanical advantage against lateral forces: ▪ 2 centrals and 2 laterals: one segment ▪ Canines: two independent segments ▪ Premolars and molars: two segments ­ Canine loss (not important): o Must be compensated for o Canine + lateral + 1st premolar loss → 3 implants (if length is insufficient, use the canine body) o Lateral + canine loss → two small implants (avoid a single large implant and cantilever) o Canine is the key position in completely edentulous mouths o Canine key position in overdentures ­ First molar loss: o 10-12 mm MD width o Two teeth are considered and play a key role o In planning the second molar loss is included even if it is a terminal tooth o In gaps greater than 14 mm → 2 implants are placed ­ Edentulous maxilla: o Forces come at an angle to the anterior region o Generally,→ implant lengths are shorter compared to the mandible o Therefore, there will be a lot of stress and destruction o 3 times more destruction compared to the mandible o İt’s essential to place implants in the canines, first molars, and at least 1 implant in the central region ­ Edentulous mandible (not important): o More advantages than maxilla o Lock implants are utilized in canines and molars in the all-on four technique o Three rimes more durable structure compared to maxilla o However, if forces exceed a medium level → it may become more sufficient ­ Patient risk factors: o Parafunction (bruxism, clenching) o Dynamics of masticatory muscles (gender, age, muscle mass) o Vertical crown height (longer crowns cause more stress) o Position in arch (stress increases from anterior to posterior) o Opposing occlusion ­ Bone density: o D4 bone: ▪ 10 times weaker ▪ Limited bone contact ▪ Incompatible with titanium’s elastic modulus o D3 bone: ▪ 50% weaker ▪ Limited bone contact ▪ Titanium elastic modulus somewhat closer In red → Important! Haneen Ali o D2 bone: ▪ Ideal ▪ Good bone contact ▪ Titanium elastic modules is close o D1 bone: ▪ Best result ▪ Best bone contact ▪ titanium elastic modules very good ­ Presence of weak bone: o Do more implants or larger diameter ­ Edentulous mandible treatment: o 5-9 implant o Minimum of 4 implants between the dental foramina o In case of cantilever use → maximum A-P distance should be maintained o Generally, second molars are not planned o A minimum of 2 pieces are required ­ Edentulous maxilla treatment: o Ideal plan → doesn’t include cantilever o Using one or more implant posteriorly is important for stress management o Key implant positions: ▪ 2 first molars, 2 canines, central incisor ▪ Secondary implant positions: extreme force factors ­ Independent crowns: o Hygienically advantageous o 8% of patients use dental floss daily o 90% never use it o Can be repaired individually in single crowns o There is a compatibility issue with splinted designs o Single treatment in case of failure ­ Splinter crowns: o Increases the functional surface area of the support o Increases the AP distance (AP spread) o Increases the retention of the prosthesis o Facilitates removal of the prosthesis in case of abutment screw loosening o Reduces the risk of marginal bone loss o Reduces the risk of porcelain fracture o Reduces the risk of abutment screw loosening o Reduces the risk of implant component fracture o Facilitates the treatment of implant failure complications  Haneen Ali 7th lecture: Implant body size: biomechanical and aesthetic rationale (Dt. Burcu): ­ An important indicator of stress → increase in screw fracture ­ Treatment plan sequence: o Prosthesis, implant position, patient strength factor, bone density, number of implants, size of implant ­ Stress → tension → complication: o Bone loss o Fractures of implants and components o Abutment screw loosening o Implant failure o Porcelain fracture o Decemented restorations ­ Implant body fracture related to amount of force and the diameter of implant ­ The implant emergence profile (contour of implant restoration as it emerges from the gingiva) is influenced by the diameter of the implant ­ Force characterization: o Force magnitude, force duration, force type, force direction, force ratio ­ Bite force: o Average bite force: 10-350 lb o Anterior: 25-35 lb o Canine: 100 lb o Molar: 200 lb ▪ Diameter of posterior implants should be larger than the anterior o Parafunction: 1000 LB ­ If fracture risk is high → implant diameter should be increased ­ Bone is most resistant to compressive forces ­ Shear forces are the most harmful ­ In cantilever prosthesis, implant diameter should be increased to compensate extra stress ­ As the angle increases → lateral components of the force also increase ­ Lateral components are responsible for tension and the most damaging shear force ­ Due to anatomical limitations, implants may need to be angulated. ­ To compensate for the negative effects of angulation, the diameter and number of implants should be increased ­ Stress= force/area: o Increasing the surface area through an increase in implant length and diameter is possible to reduce stress o As length of implant increases → functional surface area also increases o The study by Tada et al. shows that changes in implant length have a greater effect in less dense bone o As bone density decreases → stress will distribute around the implant and spread more apically o D1 and D2 bones are particularly found in the anterior mandible, where bone length is greater ▪ However, stresses around the implant distribute to 7-9 mm, and there is no need for implants longer than 12 mm in these areas ▪ There is a risk of excessive heat during drilling in D1 and D2 bone ▪ In the anterior mandible, there is a risk of perforation with longer implants due to anatomical limitations o In the posterior mandible, where D3 and D4 bone density is present, the inferior mandibular nerve can be repositioned to accommodate longer implants In red → Important! Haneen Ali ­ Short implants: o Short implants have a higher failure rate than long implants o Used only in specific cases that have anatomical limitations ­ Causes of failure: o Reduced surface area o Greater bite force in the posterior region o Lower bone density in the posterior region o Increased crown length ­ Advantages of short implants: o The crystalline stress pattern is similar for both short and long implants in most bone qualities o There is less need for grafting o Reduced surgical risks (such as sinus perforation and paraesthesia) o Lower risk of damage to adjacent teeth o More accurate implant positioning in the presence of fossa and undercuts o Surgical convenience o Lower cost ­ To reduce stress in short implants → the number of implants should be increased, implants should be splinted, cantilevers should be avoided, and lateral loads should be eliminated ­ Wide-diameter implant: (not important) o When implant is not stabilized o In a failed implant o In tooth extraction ­ Advantages of wide-diameter implants: o Surface area increases: ▪ Compensates for inappropriate patient strength factors ▪ Reduces the cantilever effect ▪ Increases the surface area of short implant o An appropriate emergence profile reduces the interproximal area, preventing food accumulation, bone loss, and implant fractures ­ Prosthetic advantages of wide implants: o Better emergence profile o Easier oral hygiene o Reduced risk of implant body fracture o Less abutment screw loosening ­ Wide diameter implants carry the risk of being close to the roots of adjacent teeth o Also risk of trauma and increased heat during surgical procedure ­ Narrow-diameter mini-implants: o Diameters range from 1.8 to 2.4 mm o Can be used for the fabrication of temporary prostheses o Provide support for prosthetics ­ Disadvantages of narrow mini-implants: o Long-term studies are limited in number o Often a need for immediate restorations o Reduced surface area o Less initial fixation o Higher failure rate o Limited prosthetic options o Increased risk of fracture o Higher procedural risk ­ As implant diameter increases → force on abutment screw will decrease!  Haneen Ali ­ Aesthetic: o Same as natural tooth diameter o Distance between implant and adjacent tooth root → minimum 1.5 mm o 1.5 mm of bone on facial side o Distance between 2 implants should be at least 3 mm