Optimum Teeth. New planning and treatment protocol for implant-supported restorations
2 EDI Case Studies New planning and treatment protocol for implant-supported restorations Optimum Teeth Dr Enric Catalán, Barcelona/Spain Optimum Teeth is a planning and treatment system whose objective is to eliminate post-loading complications in oral implantology, to simplify prosthodontic procedures, and to stimulate/reorganize the peri-implant bone tissue such that appropriate masticatory function is restored. Optimum (also optimal, from Latin optimus) means “the best possible”. According to several authors , periodontal disease is the most frequently observed complication of implant treatments following loading. The term “peri-implantitis” was introduced in the late 1980s . Other post-loading complications include fracture of implants, fracture or loosening of fixation screws, ceramic cracks or fractures, and halitosis  (Fig. 1). “Peri-implant disease” refers to an inflammation of Aetiological factors leading to the tissue structures surrounding an implant that has peri-implantitis been subjected to loading. For the term peri-implant disease to be applied, the implant needs to be loaded Excessive mechanical loading or in function, excluding other common types of clin- Few studies are available on mechanical overloading ical inflammatory manifestations that also result in a as an aetiological factor of peri-implantitis . Exces- loss of osseointegration but occur around implants sive loading is usually the initial mechanism induc- not supporting any forces transmitted through a ing loss of peri-implant bone tissue. The process starts restoration . The concept of peri-implant disease with the occurrence of microfractures (whether by encompasses two distinct clinical entities: axial or lateral loading) in the peri-implant bone. 1. Mucositis. Inflammation of the peri-implant Occasionally these forces will give rise to other com- mucosa, reversible if adequately treated, and not plications like fracture of the fixation screw, the involving loss of the supporting bone. ceramic material or even the implant without result- 2. Peri-implantitis. Inflammation of the peri-implant ing in bone loss or disintegration. Potential reasons mucosa, but with both clinical and radiographic for mechanical overloading are: evidence of peri-implant bone loss . Signs and • Occlusal forces, parafunction (bruxism)  symptoms (Fig. 2): • Treatment planning • Reddening of the peri-implant mucosa • Bone quantity and/or quality • Bleeding on probing • Distribution of implants  • Suppuration (occasionally) • Few implants • Deepening of peri-implant pocket • Prosthetic factors • Pain on pressure or percussion • Lever arms, cantilevers, lack of passivity • Radiology: loss of peri-implant bone height • Macroscopic implant design. The implant design • Implant mobility (in advanced cases). may frequently appear to be of secondary Fig. 1 Complications affecting implant- supported restorations.
EDI Case Studies 3 Factors promoting bacterial colonization Microscopic design – microsurface The surface roughness of the implant body and implant collar can promote adhesion of bacterial plaque if the surface remains exposed to the oral environment. Precision of fit between implant components Imprecisions between the implant and its compo- nents are capable both of permitting the passage of micro-organisms and of favouring plaque retentionFig. 2 Microleakage, oxidation, bacterial contamination. [12-14]. In 1992, Binon et al. presented a study of commer- cially available implants systems, demonstrating that importance but is essential to force transmission the mean discrepancy obtained between the implants and whether or not leakage occurs . Force and their abutments ranged from 20 to 49 µm. Con- transmission to the bone can favour mechanical sidering the size of the micro-organisms populating overloading at some location, particularly where the oral cavity (< 10 µm), these imprecisions will cre- the bone meets the platform/collar of the ate not only an entry path for micro-organisms but implant. Due to its biomechanical weakness, this also, once the system has been placed into function, critical zone facilitates the development of an exit path with emergence of a bacterial fluid osseous defects followed by superinfection [9,10]. “pump” . Other authors (Lazzara and Porter) have used theBacterial colonization of peri-implant pockets concept of platform switching in an attempt to elim-Related micro-organisms include: inate bacterial colonization of the implant-abutment1. Spirochetes interface in straight (non-tapered) connection sur-2. Motile gram-negative anaerobic bacteria (Prevo- faces . tella intermedia, Porphyromona gingivalis, Actino- bacillus actinomyctencomitans, Bacterioides for- sytus, Treponema denticola, Prevotella nigrescens, Peptoestreptococcus micros, Fusobacterium nucleatum).Colonization of the peri-implant pocket by thosemicro-organisms will not automatically lead to peri-implantitis. Rather, active and prolonged infectionassociated with rapid loss of bone height can onlydevelop in the presence of other (local, systemicand/or genetic) co-factors, notably including poorlycontrolled diabetes, smoking, prolonged treatmentswith corticosteroids, radiotherapy, chemotherapy ormechanical overloading of the implant. Patients receiving implant treatment after being Fig. 3 Tapered connection offering biomechanical stability.rendered completely edentulous due to severe perio-dontal disease are known to be negative for bothActinobaillus actinomycetemcomitans and Porphy- Zipprich et al.  studied the biomechanical behav-romonas gingivalis within the first month of per- iour of nine implant-abutment connections, eachforming the tooth extractions, which confirms that subjected to loads (angle 30°) of up to 200 N. Theviability of these micro-organisms depends on the micromovements developing at the implant-abut-presence of a periodontal sulcus. Likewise, reduced ment interface were recorded by radiography andnumbers of spirochetes and Streptococos sanguinis with a digital camera (1000 images per second). Itand mutans point in the same direction of teeth act- emerged that only the tapered implant-abutmenting as a reservoir facilitating the spread of specific connections did not present any micromovements orpathogens . microgaps (Fig. 3).
4 EDI Case Studies Fig. 5 Non-splinted crowns and abutments. Fig. 4 Optimum Teeth (planning and treatment) is based on the two most important advances made in dentistry over Fig. 6 the past 20 years, namely osseointegration and adhesion. Triple integration. Electrochemical corrosion Intimate union of a titanium implant with a non-pre- cious metal structure (having a different electric potential) in an aqueous medium like saliva will give rise to a galvanic current associated with release of ions to the medium, which increases the number of macrophages in the peri-implant region, promoting initial bone resorption . To summarize, peri-implant bone loss has a multi- factorial aetiology; both bacterial infection and excessive mechanical loading are contributing fac- 1. Achieving an excellent passive fit to eliminate tors, although no evidence is available which of both stresses in the implant and its components, using initiates the process. multiple single crowns supported by implants Optimum Teeth (planning and treatment) is based without splinting (Fig. 5). on the two most important advances made in den- 2. Designing biological implant-supported restora- tistry over the past 20 years, namely osseointegration tions without microleakage; without a gap in the and adhesion  (Fig. 4). connection; without imprecisions of fit at the A new category of materials known as ceromers abutment-crown interface; without the use of (ceramic optimized polymers) are used for layering cement; without electrochemical corrosion; and to machined titanium abutments. Being composed ensuring integration at three levels: bone-to- of an organic matrix and an inorganic filler with high implant, implant-to-abutment and abutment-to- ceramic content, they offer a similar level of wear ceromer (Fig. 6). resistance as natural teeth and a lower elastic modu- 3. Designing biodynamic and aesthetic emergence lus (Young’s modulus) than conventional ceramics. profiles with no need for prolonged use of tempo- Their functional behaviour thus compensates for rary restorations. the rigidity present at the level of the bone-implant 4. Making sure that hygiene and maintenance is ankylosis. Combining abutments with a ceromer similar to the level required in natural teeth. results in a complex with proprioceptive qualities 5. Use of biomaterials that will allow for extraoral or similar to natural teeth. intraoral modifications or adjustments. The aes- thetic veneering materials (pure ceramics) cur- Objectives rently available don’t permit subtractive or addi- tive surface treatment. Based on observations, studies and analysis of post- 6. Avoiding the simultaneous presence of materials loading complications, the following goals can be (ceramic and composite) with different physical defined to optimize rehabilitations supported by properties on the occlusal surfaces of the implant- implants: supported restorations.
EDI Case Studies 5 Fig. 7 7 8Axial CT scan for planning and guided surgery. Fig. 8 Radiographic guide with gutta-percha markers. 7. Minimizing the occurrence of post-loading compli- is to select the machined abutments correspon- cations such as peri-implantitis, screw fractures or ding (in diameter and length) to the designed loosening, ceramic cracks or fractures, and halitosis. emergence profiles. 5. With the selected abutments present on the stone To pursue the described objectives, it is necessary to cast, and together with the mesiodistal and develop a treatment plan based on: vestibulolingual diameter of the waxed-up teeth, 1. Knowledge of the patient the surgical guide is implemented. • Clinical history, indications and contraindications 6. To establish the biomechanically ideal insertion • Additional examinations (e.g. bone quantity/ axes of the implants, the location of the working quality, soft-tissue thickness) cusps of the opposing dentition is taken as refer- • Diagnostic wax-up. ence. Example: For rehabilitations with implants 2. Knowledge of the implant system at mandibular molar sites, the insertion axis of • Macroscopic design the implants will pass through the central fossa • Surface treatment of these molars, since these areas will hit the • Implant-abutment connection. (palatal) working cusps of the maxillary antago- nists. This way of relating both arches will allow The departure point of treatment planning and exe- the forces acting on the implant-supported cution based on the Optimum Teeth protocol is the restorations to be directed to the implant axis, restoration. Starting from the diagnostic wax-up, the thereby avoiding stress formation both in the implants are placed on the stone cast along their peri-implant cortical bone and in the implant- ideal biomechanical axis for tension-free support abutment connection. and absorption of functional loads. 7. Radiographic guide and 3D planning if insertion along the ideal biochemical axis is compromised Optimum Teeth clinical protocol by bone conditions (Fig. 8). 8. Antibiotic/antiinflammatory prophylaxis (two days). 1. First visit, including a clinical history and photo- 9. Surgical procedure for implant placement: graphic/radiographic documentation (Fig. 7). • Option of immediate loading (anterior seg- 2. Impressions and craniomaxillary/intermaxillary ment): a temporary abutment and crown will records. shape the soft tissue in accordance with the 3. The procedure starts out with study casts mount- desired emergence profile. ed in the articulator and with a diagnostic wax-up. • Option of delayed loading: intraoperative impres- 4. Design of the emergence profiles, taking as refer- sion of the implant platform with an impression ence profiles of adjacent teeth at the level of the post and a closed tray prior to suturing the flap. cementoenamel junction or, alternatively, if such Subsequently the impression post is removed, teeth are not present, average mesiodistal and the sealing screw inserted and the flap sutured. vestibulolingual crown dimensions. The next step An implant analogue is attached to the impression
6 EDI Case Studies 9 10 Fig. 9 Integrated and screw-retained crowns/abut- ments. Fig. 10 Radiographic detail of non- splinted crowns and abutments. 11 12 Fig. 11 Previous radiographic examination. Fig. 12 Implant-supported crowns with bilateral sinus floor elevation. post and positioned into the tray. Then the implant epithelial and connective-tissue union impression is poured in stone to obtain the mas- by repeated insertion and removal of different ter cast. After eight to ten weeks: Delivery of the components (such as healing abutments or screw-retained crowns (machined titanium impression abutments). The soft tissue will abutments with ceromer layered to their sur- adapt to the ideal emergence profile rather than face). The screw channels of the crowns and the other way around, as commonly observed abutments are obturated with the same with healing abutments (Fig. 10). ceromer, such that a single biomaterial will be present for aesthetic veneering in the occlusal The integrated crown abutments are not splinted, area of the crowns. In the occlusal area of screw- such as to allow an excellent passive fit and eliminat- retained ceramic crowns, two materials with dif- ing all stresses known to develop when superstruc- ferent physical properties are simultaneously tures are splinted. To avoid the use of splinted super- present. The erosion properties of the composite structures, the biological behaviour is optimized by obturating the channels differ from those of the not using different metals with different electric ceramic material. With time, this will provoke potentials that in contact with saliva would provoke, changes in vertical dimension, premature con- to a more or less pronounced degree, electrolytic cor- tacts and interferences with subsequent biome- rosion. chanical overloading of the implant-crown-abut- These implant-supported crowns behave much like ment complex (Fig. 9). Thanks to the modifiable natural teeth (excellent passive fit), without requir- nature of ceromers, the restorations can be fin- ing cement for adjustment, without imprecisions of ished without previously conducting a try-in. The fit in the peri-implant biological area, with optimal objective of intraoperative impression-taking is long-term maintenance, without corrosion, and to implement (using the layering technique) the allowing for timely modification in both the occlusal crowns on the abutments in the phase of and the aesthetic crown areas (Figs. 11 to 15). osseointegration. The second surgical procedure Designing an optimal emergence profile (without is used to immediately deliver the implant-sup- temporaries, elliptical, without discrepancies and with- ported crowns, which will feature ideal emer- out cement) is essential to the stimulation and trabec- gence profiles without a need for temporary ular reorganization of peri-implant bone tissue and to restorations and without disrupting the peri- obtain healthy soft-tissue structures (Figs. 16 to 19).
EDI Case Studies 7 Fig. 13 13 14 Single material in the occlusal area. Fig. 14 Soft-tissue health. Fig. 15 Vestibular detail. Fig. 16 16 17 Schematic representation of an ellipticalprofile stimulat- ing trabecular reorganization. Fig. 17 Healthy soft tissue (detail view). Fig. 18 18 19 Elliptical emergence profile. Fig. 19 Integrated and screw-retainedcrown/abutment (first premolar). Acknowledgements Contact address Dr Enric Catalán I would like to thank all my teachers and friends at Avenida Diagonal 343 the Círculo Odontológico de Barcelona for everything 08037 Barcelona they have taught me in the past, and for everything Spain I expect them to teach me in the future. Special Phone: +34 93 2076179 email@example.com thanks to Dr Marian Lorente and Margarita Cubías for their collaboration and confidence in developing the Optimum Teeth protocol. A list of references can be found on www. teamwork-media.de