Practical Procedures in Implant Dentistry. Группа авторов
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imaging with cone beam computed tomography (CBCT) scans in combination with the use of planning software allows 3D positioning for the prosthetically planned approach. Improved safety and predictability in implant insertion has resulted. The use of surgically guided templates to provide precise implant placement with alignment in the correct axis enhances predictability and reliability in placing implants that are bodily within bone, and with access alignment that may allow screw retention. It also allows the clinician to diagnose whether augmentation may need to be undertaken in either a simultaneous or staged approach with implant placement.
Importance of the soft tissue interface: It is now understood that the peri‐implant soft tissues are paramount for long‐term stability and predictability. The soft tissue interface is similar to that of natural teeth and a barrier to microbial invasion. Histologically, peri‐implant tissues possess a junctional epithelium and supracrestal zone of connective tissue. This connective tissue helps seal off the oral environment, with the fibres arranged parallel to the implant surface in a cuff‐like circular orientation. This arrangement may impact how the tissue responds to bacterial insult or cement extrusion into the sulcus. Natural teeth have gingival fibres inserting into cementum tissues, but because of the parallel arrangement of fibres around implants the tissues are more easily detached from the implant surface. This may lead to breakdown such as that seen in peri‐implantitis or cement extrusion. This inflammatory breakdown is often seen at an accelerated rate compared to that of periodontitis. Literature has also demonstrated the presence of a ‘biologic width’ around dental implants, and understanding the influence of thick tissue will help prevent bone loss and provide improved stability [2, 3].
Implant design: Both macrostructure and microstructure of implants have undergone continuous development to attain better primary stability, quicker osseointegration, and increased bone–implant contact. Micromotion may disturb tissue healing and vasculature, with micromotion greater than 100–150 μm detaching the fibrin clot from the implant surface. Modern implant designs have focused on achieving enhanced primary stability, with manufacturers developing a tapered implant that allows for the widest part of the implant to engage the cortical bone at the crest, while the apical portion is tapered to allow the trabecular bone to be compressed. The original implant connections were an external hex, however modern implant designs have focused on platform‐switched internal connections. These are often conical connections, with several manufacturers’ designs approaching a Morse taper. This creates significant friction through the high degree of parallelism between the two structures within the connection. It has been shown to reduce the microgap size and distribute stress more evenly; there is also increasing evidence that it helps to preserve peri‐implant bone and stabilise soft tissues. Extensive research into implant microstructure has established the optimal environment for bone–implant contact, with both additive and subtractive techniques used to develop moderately rough surfaces (Sa 1–2 μm). Most implant manufacturers produce this surface by using acid etching, grit blasting, or anodic oxidation. This roughness improves the osteoconductivity of the surface.
Digital implant dentistry – computer‐aided design ( CAD ), computer‐aided manufacturing ( CAM ), chairside intra‐oral scanning, and 3D printing: This area has undergone significant technological improvements in recent years, with implant planning software allowing accurate planning of dental implants using CBCT. The ability to print surgical guides through 3D printing is now commonplace, with many dental practices able to access this technology due to the reduced cost of printing. CAD/CAM fabrication of prosthetic abutments and implant bars allows customised designs that are passively fitting, economic, and homogeneous, with no distortion compared to that of cast metal frameworks. The many different materials dental clinicians have available to mill nowadays, including zirconia, ceramics, hybrid ceramics, cobalt‐chrome, and titanium, allow the modern clinician to select appropriate materials for both aesthetics and strength when required.
Loading protocols: The original protocols demanded an unloaded period of healing after implant surgery that ranged from three to six months. With the improved designs possessing better primary stability and roughened surface implants, these delayed loading protocols have been challenged, with immediate loading of implants providing immediate function in the first 48 hours. This has led to better acceptance of treatment, with reduced numbers of appointments and intervention. Survival rates are high for immediate loaded and conventional loaded implants, however immediate loading may pose a greater risk for implant failure if there is the possibility of micromotion.
Complications and long‐term maintenance: Because the original implant patients were treated over 50 years ago now, many patients have had implants for multiple decades. Complications are known. These can be mechanical in nature, such as screw loosening/fracture, veneering material fractures and wear, or biological complications with peri‐implantitis and inflammation. Proper planning minimises such failure and complications. Patients should still understand that regular continuing care is required and that their implant treatment may require servicing and may even need replacement in the future.
We hope that this book provides the reader with information that allows their practice of implant dentistry to be successful and predictable, ultimately improving a patient's quality of life. The book has been formatted to ensure that the reader has access to relevant information in a recognisable format under the headings ‘Principles, Procedures, and Tips’. This will give practising clinicians accessible information to learn new skills, and provides a continual reference for revision prior to performing procedures. We hope this will ensure that the clinician undertakes best practice within their dental office in the field of implant dentistry.
References
1 1 Brånemark, P.‐I., Hansson, B.O., Adell, R. et al. (1977). Osseointegrated Implants in the Treatment of the Edentulous Jaw, 132. Stockholm: Almqvist and Wiksell.
2 2 Linkevicius, T., Apse, P., Grybauskas, S., and Puisys, A. (2009). The influence of soft tissue thickness on crestal bone changes around implants: a 1‐year prospective controlled clinical trial. Int. J. Oral Maxillofac. Implants 24 (4): 712–719.
3 3 Tomasi, C., Tessarolo, F., Caola, I. et al. (2014). Morphogenesis of peri‐implant mucosa revisited: an experimental study in humans. Clin. Oral Implants Res. 25 (9): 997–1003.
2 Patient Assessment and History Taking
Christopher C.K. Ho
2.1 Principles
Careful patient selection, evaluation, and treatment planning are fundamental to the success of implant therapy and will help to avoid future complications or failures. Since Brånemark et al. [1] published research documenting successful osseointegration on endosseous titanium implants in 1969, the use of osseointegrated dental implants has increasingly become the treatment option for the replacement of missing teeth. Despite the predictability of dental implants, a small but significant number of patients continue to experience implant failure, and it is important to understand the risk factors involved. Informed consent is the process of communication between a clinician and a patient whereby a patient grants permission for the proposed treatment based on understanding the nature of the problem, the risks, and the benefits of the procedure and treatment alternatives, including no treatment.
The first objective is to gather all relevant information to plan treatment. It is essential to obtain appropriate information about the patient's dental and medical history, and to conduct a comprehensive examination in conjunction with diagnosis from radiographic imaging and study casts.
2.1.1 Medical History
The general health status of a patient should always be assessed prior to any surgical procedure. Although there is minimal association between general health status and implant survival [2], there are certain situations where implant procedures may risk the health of a patient or possibly be associated with higher failure rates of osseointegration.
Medical questionnaires