Dental Implants- part I and II: Biological and surgical aspects

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1. DENTAL IMPLANTS PART 1: BIOLOGICAL ASPECTS DR. ANTARLEENA SENGUPTA, PG

2. CONTENTS INTRODUCTION PARTS OF IMPLANT CLASSIFICATION BIOLOGICAL ASPECTS Macrodesign - implant geometry Microdesign History Additive processes Subtractive processes Hard and soft tissue interface

3. INTRODUCTION Per-Ingvar Brånemark (1950, Sweden)   achieved an intimate bone-to-implant apposition that offered sufficient strength to cope with load transfer  called “osseointegration.”   First edentulous patient treated (mandible)—1965 : inserted screw-shaped, commercially pure titanium implants in the symphysis and left covered for a few months. Titanium abutments were placed, on top of which a fixed prosthesis could be screwed within 6 months and lasted 40 years. Brånemark et al. Osseointegrated implants in the treatment of the edentulous jaw: Experience from a 10-year period.  Scand J Plast Reconstr Surg.  1977 Definition: 1. An alloplastic material or device that is surgically placed into the oral tissue beneath the mucosal or periosteal layer or within the bone for functional, therapeutic, or esthetic purposes. OR 2. To insert a graft or alloplastic device into the oral hard or soft tissues for replacement of missing or damaged anatomical parts, or for stabilization of a periodontally compromised tooth or group of teeth. (Glossary of Periodontal Terms-8)

4. PARTS OF A DENTAL IMPLANT (C.E. Misch & C.M. Misch, 1993)

5. CLASSIFICATION A- Depending on their placement within the tissues Endosseous Root form Blade (Plate) form Ramus frame Subperiosteal Unilateral Complete Circumferential Transosteal Staple Pin (single) Multiple pin

6. B- Depending on the materials used Metallic implants – Titanium, Titanium alloy, Cobalt Chromium Molybdenum alloy. Non- metallic implants – Ceramics, Carbon etc. PEEK implants CLINICAL ADVANTAGES of PEEK over Ti : causes fewer hypersensitive and allergic reactions. radiolucent –fewer artifacts on magnetic resonance imaging Non-metallic appearance– more aesthetic versatile foundation material– can be tailored to a particular purpose by changing its bulk or surface properties. ( Rahmitasari et al., 2017)

7. C- Depending on their reaction with bone

8. D- Depending on treatment options ( Misch’s Classification, 1989) 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 hyper contoured 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 gingival, but may be made of porcelain, or metal. RP-4: Removable prosthesis; overdenture supported completely by implant. RP-5: Removable prosthesis; overdenture supported by both soft tissue and implant.

9. MACRODESIGN OF IMPLANTS Implant Geometry BIOLOGICAL ASPECTS

10. BLADE IMPLANTS Given by Linkow (1968) One or several posts pierced through the mucoperiosteum after suturing of the flaps DISADVANTAGES:   Because the high-speed drilling leads to ample bone necrosis at the histologic level, fibrous scar tissue formation occurs. This allows downgrowth of the epithelium, which leads to marsupialization of the blade implants.  If a bacterial infection occurs, it can lead to an intractable periimplantitis with ample bone loss.   removal of such implants after complications implies sacrificing surrounding jawbone.   Because of its retentive geometry, the blade implant cannot simply be extracted or removed by a trephine, as with a cylindrical or screw-shaped implant.

11. PINS Seldom used at present DISADVANTAGE: Similar to blade implants, the bone necrosis during drilling leads to fibrous encapsulation, marsupialization, and loss of the implants because of infections.   ADVANTAGE: when such implants must be removed, removing the connection at the place of convergence is sufficient to allow easy extraction of each individual pin. Thus, bone loss from removal is minimal.

12. CYLINDRICAL IMPLANTS 2 types- HOLLOW and FULL. Straumann et al, 1970: ITI (International Team for Implantology) system  hollow cylinders   Rationale: Implant stability would benefit from the large bone-to-implant surface provided by means of the hollow geometry. The holes (vents) were believed to favor the ingrowth of bone to offer additional fixation.   Similar concept: Core-Vent system ( Niznick , 1982)   Studies showed disappointing survival statistics with the hollow cylinders. ( Piatelli , 1999; Telleman , 2006 ) Full cylindrical implants (Kirsch, 1989) marketed as IMZ, referring to the “internal mobile shock absorber.”   Although early results were encouraging (symphyseal area), the long-term survival rates became unacceptable ( Willer, 2003; Park, 2005 )—limited use currently.

13. DISK IMPLANTS Rarely used currently. Given by Scortecci (1999) Rationale: lateral introduction into the jawbone of a pin with a disk on top. Once introduced into the bone volume, therefore, the implant has strong retention against extraction forces.   DISADVANTAGE: cutting of the bone by means of high-speed drills leads to a fibrous scar tissue surrounding the implant, as revealed frequently by peri-implant radiolucencies . Data on the clinical success of disk implants are mostly anecdotal.

14. SCREW-SHAPED (Tapered) IMPLANTS Currently, the most common implant is the screw-shaped, threaded implant. Currently discussion is ongoing about the ideal thread profile (mostly in vitro or finite element analysis studies) Very good long-term (>15 years) clinical data available for a screw-shaped implant ( Brånemark system)— Ravald et al, 2013; Winitsky et al, 2018 Decrease in interthread distance at the coronal end of the implant has been shown to enhance the marginal bone level adaptation Tapered implant forms have been used primarily because they require less space in the apical region No clinical data tend to support a superior success rate with tapered versus straight oral implants.

15. SUBPERIOSTEAL IMPLANTS customized according to a plaster model derived from an impression of the exposed jawbone, prior to the surgery planned for implant insertion. Several posts, typically four or more for an edentulous jaw, are passed through the gingival tissues.   designed to retain an over-denture, although fixed prostheses have also been cemented onto the posts. DISADVANTAGES: As a result of epithelial migration, the framework of subperiosteal implants usually becomes surrounded by fibrous connective tissue (scar), including the space between the implant and the bone surface. The marsupialization, as described earlier, often leads to infectious complications , which often necessitates removal of the implant.   while being loaded by jaw function, jawbone resorption occurs rapidly , resulting in a lack of adaptation of the frame to the bone surface.   now rarely used.

16. TRANSMANDIBULAR IMPLANTS developed to retain dentures in the edentulous lower jaw. applied through a submandibular skin incision and required general anesthesia. Two models were available. First  “Staple-Bone” implant (Small, 1975) reported implant survival rate >90% after 15 years Bosker model (1989) less reliable, achieving only 70% survival after 5 years in the symphyseal areas as seen in the follow-up analysis

17. MICRODESIGN OF IMPLANTS Implant surface characteristics key element in the reaction of hard and soft tissues to an implant   Some materials can have   toxic cellular side effects   bio-compatibility – “passive” tissue-healing enhance bone apposition at the implant surface in an osteoconductive manner.

18. HISTORY Before Brånemark clarified osseointegration, researchers focused on surface characteristics to obtain bone apposition.   Titanium, preferably commercially pure (CP) titanium , became the standard for endosseous implants (1981) in periodontology .   Ti is a very reactive material – undergoes instantaneous surface oxidation creates a passivation layer of titanium oxides, which have ceramic-like properties, making it very compatible with tissues.

19. ADDITIVE PROCESSES Modification of the chemical nature of the implant surface by coating its surface. E.g., hydroxyapatite (resembles bone tissue). Osteoblastic cell response—varies acc. to Ca : PO4 ratio (in vitro studies— Boyan 2016, MacBarb 2017) Use of increased or modified titanium oxide (TiO2) layers –enhance/accelerate osteogenesis (Huang et al, 2005). This is achieved by anodizing or chemical processing.   The oxide content of the TiO2 layer is essential for nucleation processes to form calcium phosphate precipitates  mineralized bone formation.   Another line of research involves integrating fluoride in the TiO2 layer . These ions can be displaced by oxygen originating from phosphates, thus achieving a covalent binding between bone and implant surface. Hall et al, 1995   Fluoride release is also known to inhibit the adhesion of proteoglycans and glycoproteins on the hydroxyapatite surface, two macromolecules known to inhibit mineralization. Embery & Rolla, 1980

20. SUBTRACTIVE PROCESSES These are the manufacturing processes to obtain a proper implant surface vary from machining (called “turned” for screw-shaped implants) to acid etching and blasting. It is not known what degree of micro-roughness is ideal for bone adhesion; this depends greatly on the chemical nature of the implant. ( Ellingsen , 1991) Acid etching and blasting alter the microroughness of the implant surface. Their effect cannot be limited to this, however, because these processes can also modify the surface chemistry to a certain extent. Nevertheless, their impact on surface roughness predominates, which is why they are applied.

21. IMPLANT SURFACE CHEMICAL COMPOSITION Studies on oral implants made of carbon or hydroxyapatite—so far unsuccessful. ( Ong et al, 2000 ) lack of resistance to occlusal forces  frequent fractures. So-called noble metals or alloys, on the other hand, do not resist corrosion and have thus been abandoned. vast majority of oral implants are made of commercially pure ( c.p. ) titanium , this type is the focus of ongoing clinical research and discussion.

22. PROPERTIES OF TITANIUM IN DENTAL IMPLANTS Highly reactive metal that oxidizes within nanoseconds when exposed to air- passive oxide layer  corrosion resistance in c.p. form . Ti6Al4V (for titanium- aluminum 6%, vanadium 4%) – provoke bone resorption because of leakage of some toxic components. The oxide layer of c.p. titanium reaches 10 nm of thickness. It grows over the years when facing a bioliquid. It consists mainly of titanium dioxide. All titanium oxides have dielectric constants, which are higher than for most other metal oxides. The biomolecules normally appear as folded-up structures to hide their non-soluble parts, while putting water-soluble radicals on their surface. Thus, they will adhere to the TiO2 surface after displacing the original water molecules sitting on its surface. Initially—weak van der Waals forces are acting, the high dielectric constant of titanium oxides and the polarizability of the molecules after adsorption will lead to high bond strengths , which are considered irreversible when they surpass 30 kcal/mol. ( Kasemo , 1983)   To date, clinical results with CaP -coated implants have not been encouraging in a long-term perspective. ( Block and Kent, 1994; Lopez-Valverde, 2021 ) For good-quality bone, after 15 years of follow-up, clinical success rates of 99% have been reported for implants with a turned surface ( Lindquist et al, 1996) Enhanced implant surface characteristics are likely to be most beneficial for the more challenging situations, such as poor-quality bone and early and immediate loading.

23. SURFACE FREE ENERGY Surface free energy, or “wettability,” is an important parameter for these interactions—assessed through the shape of a standardized drop of liquid put on the clean implant surface. The angle of this drop toward the underlying surface reveals that the cohesive forces between liquid molecules are stronger than the adhesive forces between the liquid and the surface. Thus, a ball-shaped drop would reveal a low surface free energy. 

24. Microscopic roughness at the cellular and molecular level is defined by surface topography — measured with a profilometer, a stylus that follows the surface and measures the peak-to-valley dimensions (expressed as Ra values) or the spacing between irregularities (expressed as Scx values) Roughened implant surfaces speed up the bone apposition MICROSCOPIC ROUGHNESS

25. (in vitro) more prostaglandin E2 (PGE2) and transforming growth factor beta (TGF-β1) are produced on roughened than on smoother surfaces Roughened surfaces also show some disadvantages, such as increased ion leakage and increased adherence of macrophages and subsequent bone resorption in vitro adsorption of fibronectin was higher on smooth than on roughened, commercially pure titanium surfaces.— Francois, 1997 Micro-topography also influences the number and morphology of cell adhesion pseudopods and cell orientation. Grooves in an implant surface will guide the cell migration along their direction. Bone growth can enter altered microtopographic features such as pits and porosities with internal dimensions that are only a few microns

26. HARD TISSUE INTERFACE

27. STAGES OF BONE HEALING AND OSSEOINTEGRATION Any bone wounding  inflammatory reaction  bone resorption  activation of growth factors  attraction by chemotaxis of osteo-progenitor cells to the site of the lesion. In bone fracture, osteoblast differentiation  reparative bone formation  fusion of both ends. In implant insertion into a prepared hole  bone apposition onto the non-toxic implant surface. COUPLING effect: favors apatite crystal integration in the collagen network. E.g., osteocalcin (ECM protein) modulates apatite crystal growth The material that offers the best biologic attachment to bone and gingival tissue is titanium – layer of TiO2 The ability of a titanium rod to integrate into bone depends on host reaction to the surgical insult at the time of bone preparation ability to stabilize the rod during the early wound-healing stage. A threshold may exist in the amount of stability required of the implant in the early wound-healing process. Cell Kinetics and Tissue Remodelling

28. INITIAL BONE HEALING Interface micromovements >150 mm no differentiation to osteoblasts  fibrous scar tissue formed between the bone and implant surface  hence , occlusal load during the early healing period should be avoided. neighboring bone has been overheated/crushed ( critical temp = 47° C for 1 min—temp at which alkaline phosphatase denatures—main osteocyte enzyme ) during drilling  necrotic  prevent ingrowth of stem cells  scar/sequestered formation.   profuse cooling with intermittent moderate-speed drilling with sharp drills. Microbial contamination jeopardizes the normal bone repair  strict asepsis should be maintained. Initially, immobility of the implant surface toward the bone should be maintained. mild inflammatory response may enhance the bone-healing response, but detrimental above a certain threshold. For proper healing, the limited damage to bone tissue must be cleared up by osteoclasts—these resorb bone at a pace of 50 to 100 mm per day. Hence there is a coupling between bone apposition and bone resorption pre-osteoblasts (from invading primary mesenchymal cells) depend on a favorable redox potential of the environment-- requires proper vascular supply and O2 tension If the favorable conditions are not met primary stem cells may differentiate into fibroblasts implant (or the bone fracture surfaces) will be facing scar tissue  implants will eventually be connected to the outer environment  potential for infection.

29. woven bone is quickly formed in the gap between the implant and the bone. grows fast, < 100 μm /day, and in all directions. characterized by a random orientation of its collagen fibrils, high cellularity, and limited degree of mineralization. Limited mineralization  bone's biomechanical capacity is poor,  occlusal load should be controlled. Woven bone can grow by apposition, originating from the bone lesion or by conduction, using the implant surface as a scaffold. Factors influencing bone apposition: material properties, surface free energy, and roughness profile. Altered implant surface topographies  g reater bone apposition to the implant surface as compared to a “turned” or machined surface.

30. 2) After 1 to 2 months , this is progressively replaced by lamellar bone under the load stimulation the woven bone surrounding the implant will slowly transform into lamellar bone. Parallel layers of collagen fibrils characterize the latter, each with their own orientation, occurs at a slow pace of a few microns per day. 3) A steady state is reached after about 1.5 years—occlusal load is allowed as soon as 2 to 3 months (mostly woven bone). Research involving light microscopy has revealed an intimate bone-to-implant contact

31. THEORIES OF OSSEOINTEGRATION DISTANT OSTEOGENESIS CONTACT OSTEOGENESIS Osteogenic cells line old the bone surface. The blood supply to these cells is between the cells and the implant. Hence the bone is laid down on the old bone surface itself. Osteogenic cells are first recruited to the implant surface. The blood supply is between the cells and the old bone, hence new ( de novo ) bone is laid down. FIBRO-OSSEOUS INTEGRATION ( Linkow , 1970) OSSEOINTEGRATION ( Branemark , Zarb , Albrektsson, 1985) Fibro-osseous integration refers to a presence of connective tissue between the implant and bone. If osseointegration does not occur or osseointegration is lost for some reason, a fibrous connective tissue forms around the implant. organization process continues against the implant material, possibly resulting from chronic inflammation and granulation tissue formation & osseointegration will never occur. Osborn and Newesely (1980) Theories regarding the bone-implant interface

32. PHASES OF OSSEOINTEGRATION OSTEOPHYLLIC PHASE OSTEOCONDUCTIVE PHASE OSTEOADAPTIVE PHASE Initially : hematoma between the implant and the bone and only small amount of bone is in contact with the implant. 1 week: the body mounts a generalized inflammatory response. 2 weeks: woven bone with primary osteons has formed at the base of the surgical site and also in the furcation site of the implant surface. 4 weeks: newly-formed woven bone which lines most parts of the implant surface. 8 weeks: typical secondary osteons with concentric lamellae and a central Haversian canal can be observed in the lamellar bone. 4 months: The bone cells lay down the osteoid and spread along the metal surface. The newly formed lamellar bone, next to the implant, is continuous with the more lightly stained old bone tissue. In the apical bone marrow part of the site, a thin rim of lamellar bone can be seen in contact with the implant surface. When the implants are exposed and loaded after 4 months, there is reorientation of vascular pattern and the woven bone thickens in response to load transmission and thus bone remodeling occurs.

33. BONE REMODELING & FUNCTION Rigidity and Strength of Established Interface Factors determining success and survival of implant: primary and secondary stability.   Primary stability is that which is achieved at surgery. depends on bone quality and available volume relation between drill and implant diameter implant geometry. quantity of bone-to-implant contact area . Dense cortical bone (symphysis)  guarantees a rigid primary fixation questionable with an eggshell cortex in the maxillary tuberosity  reflected in poorer clinical outcome observed for implants in the posterior maxilla ( Pabst et al, 2015 ).

34. Compressive stresses at the implant-to-bone interface : By using an undersized drill in soft bone for preparation of the osteotomy site achieves a slight local compression, which enhances the initial stability of the implant. can result in hoop stresse s  may lead to necrosis because of the compromised vascular supply and microfractures. 4. Overloading: Longitudinal studies indicate that during the first weeks for one-stage implants, decreased rigidity can be observed (Friberg, 1999). Subsequently, rigidity increases and continues to increase for years.  “early bone resorption” Hence, when a prosthesis is installed immediately (in 1 day) or early (in 1-2 weeks), care must be taken to control against overload. Overload (improper superstructure design or parafunctional habits)—cause microstrains and microfractures  bone loss of the bone at the interface to fibrous inflammatory tissue. Lack of load can also be detrimental and can lead to cortical bone resorption—called “stress shielding”. Well- accepted in orthopedics , evaluation for dental implants pending research.

35. Swami V et al., Current trends to measure implant stability. The Journal of the Indian Prosthodontic Society. 2016 Apr ASSESSMENT OF IMPLANT BIOMECHANICS a. Non-invasive methods The surgeon's perception: based on the cutting resistance and seating torque of the implant during insertion. A perception of “good” stability may be heightened by the sensation of an abrupt stop when the implant is seated. Radiographical analysis/imaging techniques : numerous limitations– periapical or panoramic views do not provide information on a facial bone level—bone loss at this level precedes mesiodistal bone loss. neither bone quality nor density can be quantified with this method. c hanges in the bone mineral cannot be radiographically detected until 40% of demineralization had occurred. (Wyatt and Pharaoh,1998) Computer-assisted measurement of crestal bone level change may prove to be the most accurate radiographical information. However, this method is not convenient to use in clinical practice. Cutting torque resistance (for primary stability): by Johansson & Strid, 1994 – The amount of unit volume of bone removed by current fed electric motor and is measured by controlling the hand pressure during drilling at low speed. It determines areas of low-density bone and quantifies bone hardness during implant osteotomy at the time of implant placement.

36. Insertion torque measurement : mechanical parameter generally affected by a surgical procedure, implant design and bone quality at the implant site. However, it cannot assess the secondary stability by new bone formation and remodel around the implant. Reverse torque : Johansson & Alberktsson , 1987 . assesses the secondary stability of the implant. Implants that rotate when reverse torque is applied indicate that bone-implant contact could be destroyed. Seating torque test : done after implant placement. Information about the primary stability of the implant when the implant reaches its final apico -occlusal position. Modal analysis : vibration analysis, measures the natural frequency or displacement signal of a system in resonance, which is initiated by external steady-state waves or a transient impulse force. It can be performed in two models: Theoretical and experimental. theoretical modal analysis includes finite element analysis– vibrational characteristics of objects to calculate stress and strain in various anticipated bone levels. It is used in clinical studies and experiments. experimental modal analysis is a dynamic analysis — measures natural characteristic frequency, mode and attenuation-via vibration testing. It is used in nonclinical studies  in vitro  approach. It provides reliable measurement Percussion test : simplest method. based upon vibrational-acoustic science and impact response theory. clearly ringing “crystal” sound indicates successful osseointegration, whereas a “dull” sound may indicate no osseointegration. Drawback: subjective. Pulsed oscillation waveform (POWF) : Kaneko, 1991. – analyze the mechanical vibrational characteristics of the implant-bone interface using forced excitation of a steady-state wave. Resonance and vibration generated from the bone-implant interface of an excited implant are picked up and displayed on an oscilloscope screen. It is used for  in vitro  and experimental studies.

37. x. PERIOTEST Periotest (Gulden, Bensheim , Germany) projects a rod against the implant or abutment using a magnetic pulse at a certain speed. The apparatus measures the deceleration time needed before the rod comes to a standstill. This is transformed in an arbitrary unit, which reflects the rigidity of the bone-to-implant continuum. Values should be below +7, the minimum, with the most rigid being −8.

38. XI. Resonance frequency analysis (RFA) based on basic vibrational theory consists of a transducer that could be excited using a steady state, swept frequency waveform and its response measured to determine the stiffness of an implant in the surrounding tissues. designed to be attached to an implant or abutment performance was controlled using a dedicated frequency response analyzer. originally used an L-shaped transducer that was screwed to an implant or its abutment. Til date four generations of RFA have been introduced. Major drawback of the first- and second-generation RFA devices was that each transducer had its own fundamental resonance frequency. third-generation device provided a small battery-driven system,--quick and simple measurements to be made with the possibility of chairside interpretation. first commercially available RFA equipment  OsstellTM , Osstell AB, Gothenburg, Sweden) was battery-driven and had new generation of transducer that was precalibrated from the manufacturer. The results are presented as the implant stability quotient (ISQ). The implant stability quotient unit is based on the underlying resonance frequency and ranges from 1 (lowest stability) to 100 (highest stability). The most recent version of RFA is wireless, where a metal rod (a peg) is connected to the implant by means of a screw connection.

39. Histologic/ histomorphologic analysis: obtained by calculating the peri-implant bone quantity and bone-implant contact (BIC) from a dyed specimen of the implant and peri-implant bone. Used in the nonclinical studies and experiments Tensional test:  measured by detaching the implant plate from the supporting bone. It was later modified by Bränemark by applying the lateral load to the implant fixture. However, they also addressed the difficulties of translating the test results to any area independent mechanical properties. ASSESSMENT OF IMPLANT BIOMECHANICS b. Invasive methods Push-out/pull-out test: investigates the healing capabilities at the bone implant interface ( Brunski et al, 2000). It measures interfacial shear strength by applying load parallel to the implant-bone interface. In the typical push-out or pull-out test, a cylinder-type implant is placed transcortically or intramedullarly in bone structures and then removed by applying a force parallel to the interface. Only applicable for nonthreaded cylinder type implants and technique sensitive. Removal torque analysis: Removal torque analysis implant is considered stable if the reverse or unscrewing torque was >20 Ncm . DISADVANTAGE: at the time of abutment connection implant surface in the process of osseointegration may fracture under the applied torque stress.

40. RECENT ADVANCES I mplatest : ( Lee SY, Huang HM, Lin CY, Shih YH J Periodontol . 2000 Apr) incorporates all of the features of a conventional impulse test into a compact, portable, self-contained probe. Data can be gathered in seconds operator independent.  Electromechanical impedance method: Boemio et al, 2011 . utilizes the electro-mechanical impedance of piezoelectric materials (work as both sensors and actuators) directly related to the mechanical impedance of the host structure.

41. Micro motion detecting device: Freitas et al, 2012 . customized loading device, consisting of a digital micrometer (Mitutoyo Absolute Digimatic , USA) and a digital force gauge (Chatillon E-DFE-025, USA) (range of 10–2500 N 0.25% resolution over range) is used to determine implant micromotion. The forces are achieved by turning a dial, which controlled the height of the force gauge. This dialed - in force i s applied to the abutment via a lever. The digital micrometer i s placed tangent to the crown of the abutment and detected the displacement after the load application Highly non-linear solitary waves (HNSW) : a granular crystal functions as a combined sensor and actuator composed of a chain of spherical particles in contact with each other with a piezoelectric gauge embedded in selected locations. Using the granular crystal, the surface of an implant with a single HNSW, and record the signals reflected from the interface between the granular crystal and the implant specimen under inspection Application for dentistry pending research

42. SOFT TISSUE INTERFACE

43. EPITHELIUM interface between epithelial cells and the titanium surface is characterized by the presence of hemidesmosomes and a basal lamina.   Histologically, studies indicate that these epithelial structures and the surrounding lamina propria cannot be distinguished from those structures around teeth— Branemark et al, 1985   capillary loops in the connective tissue under the junctional and sulcular epithelium around implants appear to be anatomically similar to those found in the normal periodontium In health, this sulcular epithelium has a thickness of about 0.5 mm, which shows transmigration of polymorphonuclear cells and more mononuclear cells

44. Between the epithelial attachment and the marginal bone is a dense connective tissue with a limited vascularity in the immediate vicinity of the implant surface. The total height of the “biologic width” is approximately 3-4mm, where about 2 mm is the epithelial attachment and about 1 mm is the supracrestal connective tissue zone.   Clinically, the thickness of the periimplant soft tissues varies from 2 mm to several millimeters Epithelial downgrowth does not occur in a healthy situation, indicating that factors other than collagen fiber bundles inserted in the root surface control this downgrowth. The apical edge of the epithelial attachment is about 1.5 to 2.0 mm of the bone margin. This means that the attachment level measurement performed with a periodontal probe will be about 1.5 mm higher than the real bone level. The average direction of the collagen fiber bundles of the gingiva is parallel with the implant or abutment surface.   Even when the fiber bundles are oriented perpendicularly (gingiva), the bundles are never embedded in the implant surface, as occurs with dentogingival and dentoperiosteal fibers around teeth.   The fiber bundles can also have a cufflike circular orientation. The role of these fibers remains unknown but it appears that their presence helps to create a soft-tissue “seal” around the implant.   At the biochemical level as well, there are no differences between the peri-implant and the periodontal soft tissues, even if some higher amounts of collagen types V and VI are noticed.  

45. VASCULAR SUPPLY and INFLAMMATION The vascular supply of the periimplant gingival or alveolar mucosa is more limited than that around teeth — often reduced due to lack of PDL. reaction patterns toward plaque at both the light microscopic and the ultrastructural level are similar to those of tissues surrounding teeth. periimplant gingival or alveolar mucosa has the same morphology as the corresponding tissues around teeth . These soft tissues also react the same way to plaque accumulation. Animal models have revealed that ligature-induced periimplantitis occurs more frequently when alveolar mucosa surrounds the implant as compared to when keratinized mucosa surrounds the implant— Warrer, 1995 —suggestive of importance of adequate keratinized tissue width around implants

46. Microbial leakage: originates from the abutment-to-implant connection in 2-stage implants. Animal studies indicate that this leakage results in an inflammatory reaction in the adjacent lamina propria—( Lindhe , 1992) increase in the content of inflammatory cells may be due to the adhesion and the proliferation of bacteria at the level of the I-A interface

47. A gingivitis lesion surrounding an endosseous implant can be a contained, non-progressing lesion. A periimplantitis lesion, on the other hand, is associated with a bacterial infection. Histologically, periimplantitis lesions demonstrate similarities with periodontitis lesions. They can be progressive lead to bone loss around the implant . Macroscopically rough implant surfaces, such as HA coated implants, seem to be associated with more significant periimplantitis problems due to the propensity of these surfaces to harbor bacteria and perpetuate the infection. Whereas the incidence of periimplantitis seems low with less rough (microscopically altered) implant surfaces even in the presence of periodontitis in the remaining natural dentition.

48. COMPARISON OF TISSUES SURROUNDING NATURAL DENTITION AND OSSEOINTEGRATED ORAL IMPLANTS   Teeth Dental Implants Periodontal fibers Insert into cementum on the root surfaces of natural teeth 13 groups Extend parallel to the surface of the implant and/or abutment 2 groups Connection Periodontal ligaments Osseointegration Connective tissue Lower percentage of collagen fibers Higher percentage of cells More vascular Higher percentage of collagen fibers Lower percentage of fibroblasts. Looks very similar to a scar tissue Less vascular Blood supply to surrounding gingivae Three different sources (the periodontal ligament space, the interdental bone, and the supraperiosteal region) Two different sources (the supraperiosteal vessels and a few vessels from the bone) Periodontal ligament space Present Absent Resistance to mechanical and microbiological insults More resistant Less resistant Biological width (BW) JE: 0.97–1.14 mm CT: 0.77–1.07 mm BW: 2.04–2.91 mm JE: 1.88 mm CT: 1.05 mm BW: 3.08 mm Sulcus depth ≤ 3 mm when healthy Could be >3 mm depending on multiple factors Proprioception Periodontal mechanoreceptors Osseoperception Tactile sensitivity High Low Axial mobility 25–100 μm 3–5 μm Fulcrum when lateral force applied Apical third of the root Crestal bone Possible relief Pressure absorption, distribution Pressure concentration on the crestal bone (Rose LF, Mealey BL: Periodontics: Medicine, surgery, and implants, 2004)

49. SIGNIFICANCE OF A LACKING PDL AROUND IMPLANTS No resilient connection exists between teeth and jawbone  any occlusal disharmony will have repercussions at the bone-to-implant interface. No intrusion or migration of teeth can compensate for the eventual presence of a premature contact in cases of fixed prostheses in both jaws. Clinician should be reluctant to use oral implants in growing individuals as the neighbouring teeth and periodontal tissues will further erupt  occlusal disharmonies. Problematic to place one or more implants in a location surrounded by teeth that are very mobile due to loss of periodontal support, because as the teeth move away from the occlusal forces, the implant(s) will bear the entire load. Reduced tactile sensitivity and reflex function—proprioceptive fibres in PDL Concept of osseoperception Osseoperception can be considered an associated mechano-sensibility with osseointegrated implant rehabilitation (Yan et al, 2008) For implant-supported prostheses opposing complete dentures, a contribution to oral kinesthetic perception could come from the activation of mucosal receptors beneath the complete denture , and possibly periosteal and/or mucosal mechanoreceptors in the vicinity of the implant fixture. The amount of Merkel cells in the gingival mucosa were found to be significantly higher in edentulous areas than in the dentate mucosa. This increase in the number of Merkel cell population might be to compensate for the loss of teeth. Studies have shown an increase in the tactile perception capability of osseointegrated implants over time (Kingsmill et al, 2005; Muhlbradt et al, 1989; Mericske -Stern, 1998) Tactile function of oral implants: Neural receptors of the periodontium play an essential role in oral tactile function. Most receptors, which are found in the PDL, are evidently absent around the perimucosa of dental implants. In those cases, remaining receptors of the gingiva, alveolar mucosa, and periosteum may take over the role of normal exteroceptive function.

50. DENTAL IMPLANTS PART 2: SURGICAL ASPECTS DR. ANTARLEENA SENGUPTA, PG

51. CONTENTS SURGICAL ASPECTS Case types and indications Pre-treatment evaluation General principles of implant surgery 1-stage v/s 2-stage implant placement Healing following implant surgery Advanced implant surgical procedures Post-treatment evaluation and management

52. CASE TYPES & INDICATIONS SURGICAL ASPECTS

53. a. EDENTULOUS PATIENTS Complete denture Ceramic-metal fixed bridge Separate attachments on individual implant Clips etc. connected to a bar—splint the implants together. patients prefer—ceramic restoration emerges directly from the gingival tissues in a manner similar to the appearance of natural teeth.   DRAWBACKS: provide very little lip support—may not be indicated for patients who have lost alveolar bone height lack of a complete seal  phonetic problems in speech

54. b. PARTIALLY EDENTULOUS PATIENTS Single Tooth. Greater chances of success and predictability of endosseous dental implants. Reported success rates for single-tooth implants are excellent.   Goodacre et al. performed Medline literature review from 1980-2001 and 2001-17 and found the single-tooth implant success rate to be in the range of 97% —higher than any other implant restoration. The greatest challenges to overcome with the single-tooth implant restorations were screw loosening implant or component fracture.  due to increased potential to generate forces in the posterior area Solution: use of wider-diameter implants –resists tipping forces  reduces screw loosening. Also provides greater strength and #resistance due to increased wall thickness (between the inner and the outer screw thread). internal fixation of components

55. Multiple Teeth. Challenges from remaining natural dentition: occlusal schemes periodontal health status spatial relationships esthetics In general, endosseous dental implants can support a freestanding fixed partial denture. Major advantage : not invasive to adjacent teeth—preparation of natural teeth unnecessary larger edentulous spans can be restored biggest consideration: underestimation of the importance of treatment planning with regards to occlusal loads.  greater rate of multi-unit failures

56. PRE-TREATMENT EVALUATION

57. Chief complaint problem or concern in the patient's own words? patient's goal of treatment, and how realistic are the patient's expectations? Patient reported outcome measures (PROMs)? (Adapted from Tey et al., Clinical oral implants research. 2017)

58. II. Medical history At risk for adverse reactions or complications Any disorder that may impair the normal wound-healing process A thorough physical examination Appropriate laboratory tests Medical clearance for surgery Dental History history of recurrent or frequent abscesses  may indicate a susceptibility to infections/diabetes multiple restorations compliance to past dental recommendations current oral hygiene practices previous experiences with surgery and prosthetics reported history of dissatisfaction with past treatment

59. IV. Intraoral examination General principles of implant placement: Ideal implant measurements in posterior teeth Ideal implant measurements in esthetic zone Minimum distance between implant margin to adjacent tooth should be 1.5-2 mm Minimum distance between implants should be 3-4mm Buccolingually, should be placed at 2-3mm from cervical height of contour Coronoapically , should be placed at 2.5-3mm from bucco -gingival margin Atleast 7 mm of inter-occlusal/inter-arch space should be available from the shoulder of the implant to the occlusal surface of opposing tooth A buffer zone of 2-3mm from IAN or floor of sinus from implant apex should be maintained. maintain at least 1.0 to 1.5 mm of bone around all surfaces of the implant after preparation and placement. minimum of 12 mm in the posterior mandible (mandibular nerve).

60. V. Diagnostic study models VI. Hard tissue evaluation amount of available bone Visual examination to identify deficient areas whereas other areas that appear to have good ridge width will require further evaluation. excellent means of assessing potential sites for dental implants. evaluate the available space and to determine potential limitations of the planned tx—particularly useful when multiple teeth are to be replaced or when a malocclusion is present.

61. VI. Initial radiographic screening Indications: Overall anatomy of the maxilla and mandible and potential vertical height of available bone Anatomical anomalies/pathological lesions Sites where it may be possible to place implants without grafting and sites that require grafting Restorative and periodontal status of remaining teeth Length, shape, angulation, proximity of adjacent roots Most common radiograph of choice: OPG (Palmer, 2012) The best way to evaluate the relationship of available bone to the dentition is to image the patient with a diagnostically accurate guide using radiopaque markers that accurately represent the proposed prosthetic contours.

62. Standard Projections

63. Cross-sectional Imaging

64. EVALUATION OF BONE DENSITY USING CBCT Lekholm & Zarb 1985 Misch 1990, 1993

65. Newer modalities: INTERACTIVE “SIMULATION” SOFTWARE PROGRAMS SIM/PLANT IMAGES

66. VII. Soft tissue evaluation Evaluation of soft tissue augmentation I n the presence of good oral hygiene, a lack of keratinized tissue does not impair the health or function of implants .( Wennstrom et al, 1994) keratinized mucosa has better functional and esthetic results for implant restorations. ( Block et al, 1996 ) Implants with coated surfaces (i.e., HA or TPS coating) demonstrate greater peri-implant bone loss and failures in the absence of keratinized mucosa. ( Kirsch & Ackermann , 1989) Areas with minimal or no existing keratinized mucosa may be augmented with gingival or connective tissue grafts. Additionally, any mucogingival concerns, such as frenum attachments or pulls, should be thoroughly evaluated.

67. GENERAL PRINCIPLES OF IMPLANT SURGERY

68. Patient preparation in-office procedure Under local anesthesia Prior explanation of procedural risks to patient Written informed consent Implant site preparation Aseptic surgical site Pre-rinse with chlorhexidine gluconate for 30 seconds Basic Principles of Implant Therapy to Achieve Osseointegration Implants must be sterile and made of a biocompatible material (e.g., titanium). Implant site preparation should be performed under sterile conditions. Implant site preparation should be completed with an atraumatic surgical technique that avoids overheating of the bone during preparation of the recipient site. Implants should be placed with good initial stability. Implants should be allowed to heal without loading or micromovement (i.e., undisturbed healing period to allow for osseointegration) for 2 to 4 and 4 to 6 months in the mandible and maxilla, respectively.

69. patients with good plaque control and appropriate occlusal forces have demonstrated that root form, endosseous dental implants show little change in bone height around the implant. ( Adell et al, 1981) After an initial remodeling in the first year that results in 1.0 to 1.5 mm of bone reduction (described as “normal remodeling around an externally hexed implant”), the bone level around healthy functioning implants remains stable for many years, allowing implants to be a predictable means for tooth replacement. The annual bone loss after the first year in function is expected to be 0.1 mm or less. PRIMARY BONE CONTACT: After the osteotomy has been prepared, areas of the native bone structure are left exposed. When the implant is placed into the preparation, some areas of the titanium rod make contact by “ pressfit ” to the exposed native bone, called areas of primary contact. results in instantaneous osseointegration Bone formation begins to occur on the titanium surface and on the cut bone surfaces and trabeculae bone remodeling begins IN THESE AREAS—results in new bone formation along the implant surface  SECONDARY BONE CONTACT. “dip” in implant stability

70. 1-STAGE v/s 2-STAGE IMPLANT PLACEMENT SURGERY 1-stage procedure : a component of the implant is projected above the mucosa 2-stage procedure : implant is initially covered with mucosa protection of the implant during osseointegration complex cases—poor bone quality or grafted regions second-stage surgery  exposes the top of the implant abutment is attached.

71. CASE SELECTION OF IMPLANT PLACEMENT PROTOCOL

72. TWO-STAGE “SUBMERGED” IMPLANT PLACEMENT: Stage 1 Surgical Procedure

73. Flap design, incisions, and elevation INCISIONS Crestal incision: made along the crest of the ridge, bisecting the existing zone of keratinized mucosa More preferred Easy management Less bleeding, edema Faster healing Remote incision: when bone augmentation is planned to minimize the incident of exposure of bone graft

74. FLAP REFLECTION Full-thickness flap -- buccally and lingually to the level of the mucogingival junction, exposing the alveolar ridge of the implant surgical sites. Elevated flaps may be sutured to the buccal mucosa or the opposing teeth to keep the surgical site open during the surgery. The bone at the implant site(s) must be thoroughly debrided of all granulation tissue. “Knife-edge” alveolar process  a large round bur is used to recontour the bone to provide a reasonably flat bed for the implant site. < 10 mm of remaining alveolar bone, the knife-edge should be preserved. Bone augmentation procedures can be used to increase the ridge width .

75. Implant site preparation— series of drills are used incrementally Surgical guide or stent may be used to direct proper implant placement Sequence of burs- round 2-mm twist pilot 3-mm twist countersink

76. multiple implants being placed next to one another  use guide pin to check alignment and parallelism IOPAR with a guide pin or radiographic marker in the osteotomy site(s) to check relationship of osteotomy site to anatomical structures. Implants should be positioned ~3 mm between one another to ensure sufficient space for interimplant bone and soft tissue health facilitate oral hygiene procedures. initial marks should be separated by at least 7 mm ( center to center ) for standard-diameter implants

77. Sequential drilling: HIGH speeds (800-1500 rpm) VERY SLOW speeds (20-40 rpm)

78. Implant placement At slow speeds (20-30 rpm) Either by rotating handpiece or manually by torque wrench Insertion must follow the same path as osteotomy site

79. Flap closure & suturing surgical sites should be thoroughly irrigated with sterile saline. Proper closure of the flap over the implant(s) is essential. Good primary closure of the flap  tension free. achieved by incising the periosteum (non-elastic)  periosteum is released  flap becomes very elastic  able to be stretched over the implant(s) without tension. combination of alternating horizontal mattress and interrupted sutures. Horizontal mattress sutures evert the wound edges and approximate the inner, connective tissue surfaces of the flap to facilitate wound healing. Interrupted sutures help to bring the wound edges together, counterbalancing the eversion caused by the horizontal mattress sutures.

80. Postoperative care Simple implant surgery in a healthy patient usually does not require antibiotic therapy . Patients may be premedicated with antibiotics (e.g., amoxicillin, 500 mg tid ) 1 hour before the surgery and continuing for 1 week postoperatively if the surgery is extensive if it requires bone augmentation if the patient is medically compromised. Postoperative swelling  preventive measure: apply ice pack to the area intermittently for 20 minutes over the first 24-48 hours. Chlorhexidine gluconate oral rinses for plaque control, post-surgery. Adequate analgesics e.g., ibuprofen, 600-800 mg Instructions: maintain a relatively soft diet for the first few days –gradually return to a normal diet. refrain from tobacco and alcohol use for 1-2 weeks postoperatively. Provisional restorations should be checked and adjusted avoid impingement on surgical area.

81. Stage 2 exposure surgery — Flap designs: Simple Circular “Punch” Incision: areas with sufficient zones of keratinized tissue Partial-thickness repositioned flap: usually if inadequate keratinized tissue is present Objectives of Second-Stage Implant Surgery To expose the submerged implant without damaging the surrounding bone. To control the thickness of the soft tissue surrounding the implant. To preserve or create attached keratinized tissue around the implant. To facilitate oral hygiene. To ensure proper abutment seating. to preserve soft-tissue aesthetics.

82. Excess tissue over the cover screw is removed or displaced to visualise the outline of the cover screw A sharp blade is used to eliminate all tissues coronal to the cover screw  removed The head of the implant is thoroughly cleaned of any soft or hard tissue overgrowth Healing abutments or standard abutments are placed on the implant.

83. Immediate postoperative care— Reinforce good oral hygiene measures to patient around the implant. Chlorhexidine rinse to enhance oral hygiene for the initial 2 weeks while the tissues are healing. Avoid direct pressure to the soft tissue from dentures etc.—delays healing. Fabrication of the suprastructure can begin in about 2-4 weeks.

84. Maló P et al. Single-Tooth Rehabilitations Supported by Dental Implants Used in an Immediate- Provisionalization Protocol: Report on Long-Term Outcome with Retrospective Follow-Up, 2015 1-STAGE “Non-submerged” IMPLANT PLACEMENT A second intervention is not needed –implant is left exposed after the first surgery. Implants are left unloaded and undisturbed for a period similar to that for the implants placed in the two-stage approach The implant or the healing abutment protrudes about 2 to 3 mm from the bone crest , and the flaps are adapted around the implant/abutment. in posterior areas –the flap is thinned and sometimes sutured apically to periosteum to increase the zone of keratinized attached gingiva around the implant.

85. Flap Design, Incisions, and Elevation: always a crestal incision bisecting the existing keratinized tissue. Vertical incisions may be needed at one or both ends. Facial and lingual flaps in posterior areas should be carefully thinned before total reflection to minimize the soft tissue thickness. not thinned in anterior or other esthetic areas of the mouth to prevent the metal collar from showing. Full-thickness flaps are elevated facially and lingually. Implant Site Preparation: i dentical to the 2-stage implant surgical approach. The primary difference is in the placement of the healing abutment in relation to bone crest. Flap Closure and Suturing: edges of the flap are sutured with single interrupted sutures around the implant. Postoperative Care: similar to that for the 2-stage surgical approach except that the cover screw or healing abutment is exposed to the oral cavity. avoid chewing in the area of the implant(s). Prosthetic appliances should not be used in the early healing period (first 4-8 weeks). Soft lining of denture is mandatory when a one stage, non-submerged surgical approach to implant placement is used.

86. ADVANCED IMPLANT SURGICAL PROCEDURES Localized ridge augmentation Management of extractions Maxillary sinus elevation and bone augmentation Recent advances horizontal vertical Please add: Bone tapping: decision making Socket preservation technique Lateralization of nerve

87. Flap Management for Ridge Augmentation Make incisions relative to placement of barrier membranes Full thickness flap elevation at least 5 mm beyond the edge of the osseous defect Minimize vertical incisions Periosteal releasing incision– flap elasticity, tension-free closure Avoid post-op trauma for ≤ 2 weeks Wound closure: combination of mattress+interrupted sutures

88. HORIZONTAL BONE AUGMENTATION Dehiscence defects --managed during implant placement because most of the implant is covered and stabilized by native bone. If the horizontal deficiency is large and the implant placement would result in significant exposure (i.e., implant body is significantly outside the alveolar bone), it may be better to reconstruct the bone before implant placement (staged implant placement). PARTICULATE BONE GRAFT Advantages: More rapid revascularization Larger osteoconduction surface More exposure of osteoinductive growth factors Easier biologic remodeling Disadvantages: Lack rigid scaffold—easily displaced Indications: in defects with multiple osseous walls that will contain the graft in dehiscence or fenestration defects when implants are placed during the bone augmentation procedure MONOCORTICAL BLOCK GRAFT Source: intraoral or extraoral Fixed to recipient site with screws May be separated from overlying tissues with barrier membrane or covered with mucoperiosteal flap Disadvantage: biologic limitation of revascularizing large bone blocks.

89. HORIZONTAL BONE AUGMENTATION

90. VERTICAL BONE AUGMENTATION Most challenging Previous research—mostly unsuccessful: onlay block graft, particulate HA graft Recent approach: GBR Available evidence: limited

91. Distraction osteogenesis ( Ilizarov , 1954) surgical technique developed to increase vertical bone height in the deficient jaw site and Rationale : Under the proper circumstances, most cells in bone can differentiate into osteogenic or chondrogenic cells needed for repair. ( Ilizarov’s principle for deformity correction) process of generating new bone by “stretching,” referred to as distraction osteogenesis.   ADVANTAGE: no second surgical site to harvest bone newly created bone has native bone at the crest-- withstand forces better than fully regenerated bone. DISADVANTAGE:, unidirectional limitation of current devices– horizontal bone growth is difficult. High resorption—secondary grafting is required. broad use in the pre-prosthetic surgical indication with good predictability.

92. Simultaneous implant placement and GBR For implant placement in large alveolar bone defects Healing period of ≥ 6 months Modalities Use of barrier membranes Simple closure of flap Bone grafts Dahlin, 1991 : membrane treatment was far superior with regard to bone fill Palmer et al, 1994 : better results in the membrane groups; four of six sites treated with a membrane resulted in 95% to 100% elimination of the dehiscence and total coverage of the threads. In the control sites, only two of six sites showed moderate to complete bone fil l

93. MANAGEMENT OF EXTRACTIONS

94. ITI Consensus 2003 At the time of extraction Normal bone healing around implant– enhanced BIC 2 mo. after extraction Allows time for soft tissue healing Reduces total length of treatment May cause more osteogenesis 4-6 mo. after extraction Resolution of infections Prevention of soft tissue invasion Vascularization of bone graft

95. MAXILLARY SINUS ELEVATION

96. HISTORY Tatum, 1974– published by Boyne & James, 1980 Modification of Caldwell-Luc technique Tatum’s modification, 1986: transalveolar sinus floor elevation via vertical tapping Summer’s modification, 1994: specific hollow osteotomes Currently, well-accepted to increase bone volume in posterior maxilla. Indicated in case of moderate increase in interocclusal dimension.

97. CONTRA-INDICATIONS Local factors Tumor/ pathological growth in sinus Sinusitis Surgical scar/deformation of sinus cavity Periapical pathology in close proximity to sinus Severe allergic rhinitis Chronic topical steroid use Systemic factors Radiation therapy Metabolic diseases (e.g., uncontrolled DM) Excessive tobacco use Drug/alcohol abuse Psychologic/mental impairment INDICATIONS Alveolar bone height <10 mm Severely atrophic ridge and pneumatized sinus Single tooth edentulous space with 5-7 mm alveolar bone remaining

98. SURGICAL APPROACHES 1 2 3 4

99. Pre-surgical evaluation of maxillary sinus Best seen with CT/ CBCT Evaluate for pathology, masses, presence/absence of septa investigation of lateral wall for intraosseous vascular channels—avoid inadvertent bleeding due to surgical trauma. Simultaneous implant placement Implant stabilized with existing native bone– minimum 5 mm from crest Inadequate remaining bone: subsequent surgery (6 months).

100. CRESTAL OSTEOTOMY TECHNIQUE- Indirect sinus lift Moderate bone height: 7-9 mm Indicated for limited sinus bone augmentation Osteotomes used to compress bone against sinus floor “controlled inward fracture” of sinus floor bone and membrane

101. CRESTAL OSTEOTOMY TECHNIQUE

102. CRESTAL OSTEOTOMY TECHNIQUE Complications & Considerations: Acutely sloped sinus floor—may deflect osteotome Repeated tapping—bothersome to patients with dense cortex Specific complication: Benign paroxysmal positional vertigo (BPPV) Osteotome alignment—mouth opening inadequate. Offset osteotomes

103. LATERAL WINDOW TECHNIQUE- Direct sinus lift

104. Comparison of sinus elevation procedures Shenoy et al, 2020

105. RECENT ADVANCES COMPUTER-ASSISTED IMPLANT SURGERY (CAIS) Precise. Sequenc e of steps for CAIS DATA ACQUISITION IDENTIFICATION REGISTRATION NAVIGATION ACCURACY FEEDBACK

106. ADVANTAGES DISADVANTAGES Improved accuracy and safety Initial cost of the system Surgeon validation and expertise are maintained Increased installation time for surgery Security features can stop the rotary instrument in proximity to important structures Simulation can be visualized before surgery Training time is mandatory Implant position can be planned before surgery Real-time information is provided to the surgeon Accuracy depends on the various components of the system Inexperienced surgeons will improve their skill with training More challenging cases with greater comfort and confidence Inaccurate data from CT scan etc. can lead to difficulties in registration Surgical time is reduced using a surgical guide Three anatomic or fiducial markers must be visible Non-invasive surgery—with minimal or no flap reflection COMPUTER-ASSISTED IMPLANT SURGERY (CAIS)

107. DENTAL IMPLANT MICROSURGERY Scope: enhanced soft tissue management and fine suturing, drilling precision. Use of surgical microscope: immediate detection of subtle changes in drill position—feedback corrections can be done to handpiece. Drill’s angular position can be oriented relative to small landmarks—implant platform surface level, angle of adjacent cover screws. Allows optimal parallel positioning and depth of adjacent implants. Implant drill angle can be accurately oriented to angulation of root with 3-4mm of exposure (not visible otherwise without microscope) Generally flapless—minimal patient morbidity

108. DENTAL IMPLANT MICROSURGERY Scope of operation:

109. HEALING FOLLOWING IMPLANT SURGERY

110. Berglundh et al , 2007 Schupbach & Glauser , 2007

111. POST-TREATMENT EVALUATION & MANAGEMENT

112. Post-operative surgical evaluation checklist (modified from WHO checklist of surgical safety) Factors to consider in periodic recall appointments after dental implants: Clinical examination Peri-implant probing Microbial testing Stability Radiographic examination Oral hygiene and implant site maintenance

113. CONCLUSION The bone-to-implant interface plays an important role in biomechanics of the coping time for healing and loading of dental implants. The soft tissue-to-implant interfaces are also important to maintain long-term maintenance of stable marginal osseous level around implants. Clinicians must familiarize themselves with the underlying cellular and biomechanical events to evaluate the success of implant, including surgical placement, restoration and maintenance. It is essential to understand and follow basic guidelines to predictably achieve osseointegration—which apply to all implant systems. In cases of inadequate bone support, careful diagnostics and treatment planning must be done to reconstruct ridge deficiencies in order to place an implant. Future directions point towards the use of a microsurgical approach in these surgeries, which helps advance dental implants from traumatic tooth extraction towards seamless immediate replacement using such refined and digitally supported treatment modalities.

114. REFERENCES CARRANZA’S Clinical Periodontology, 10 th Edition CARRANZA’S Clinical Periodontology, 13 th Edition MISCH’S Contemporary Implant Dentistry, 1 st Edition PALMER’S Implants in Clinical Dentistry, 2 nd Edition Albrektsson et al., Biological aspects of implant dentistry: osseointegration, Perio 2000, 1994

115. THANK YOU