Spotlight on Implants

To capitalize on the recent advances in dental implant therapy, clinicians must understand their appropriate application in treatment planning and execution as well as the requisite considerations that are essential for successful outcomes.

Among US adults with missing teeth, the prevalence of dental implants has substantially increased during the past two decades-from 0.7% in 1999/2000 to 5.7% in 2015/2016.^1,2 In a recent study that projected the state of current dental implant trends a decade into the future, estimates of implant prevalence ranged from 5.7% of the population in the most conservative scenario to 23.0% in the least.¹ Dental implants have gained in popularity because, in contrast to some other treatment modalities, they preserve adjacent tooth structure and bone.^3,4 Moreover, for patients who are edentulous or partially edentulous, implant rehabilitation enhances their masticatory function and quality of life.^5,6,7 These and other benefits have resulted in dental implants becoming an important treatment option for the replacement of missing teeth.^8,9

Digitalized processes have dramatically changed how the dental profession obtains and handles diagnostic patient data. Technology effects how dentists acquire, share, and utilize patient records and aides in the development of plans for the delivery of implants and their subsequent restorations.

Among the noteworthy benefits of the advances in digital implant treatment are improved efficiencies, shortened treatment times, reduced production expenses, fewer complications, and increased patient satisfaction.¹⁰ The latter point is particularly interesting when considering that a 2-year study comparing the outcomes of digital and analog implant procedures found no significant clinical or radiographic differences.¹¹ However, patients still preferred the digital implant workflow, which reduced the active treatment time and associated costs.¹¹

It is important to note that digital technologies and implant advancements are only tools with the potential to transform time-consuming and error-prone processes into more efficient, precise, and collaborative treatments. Their capabilities are not a substitute for a thorough understanding of patient conditions, biologic and functional risks, and the long-term prognosis of proposed implant treatments. "Experience, proper training, and technology would be the ideal recipe," says Thomas Bilski, DDS, a cosmetic dentist and implantologist who practices in Independence, Ohio.

Diagnostic imaging techniques are essential tools for developing and implementing a cohesive and comprehensive treatment plan. The exceptional imaging modalities that exist today are employed to ascertain vital information during both the preoperative and postoperative phases. These imaging techniques can be categorized as either analog or digital and either two-dimensional or three-dimensional. Three-dimensional imaging has been considered the "gold standard" in implant dentistry for a variety of reasons, including the following:^12,13

It provides 3D views of the region of interest and any relevant anatomy, such as the maxillary sinus and mandibular nerve.

It facilitates estimates of alveolar bone density.

It enables a uniform magnification, multiplanar views, and the simultaneous study of multiple implants that 2D imaging cannot.

However, 3D computed tomography also has drawbacks, which include beam-hardening or scatter due to adjacent metal, high costs, and relatively high radiation doses to patients.¹⁴ Considering these limitations, the current trend in implant imaging is cone-beam computed tomography (CBCT), which offers revolutionary 3D images with axial, coronal, and sagittal views and a stream of useful data while delivering substantially less radiation to the patient.¹⁵ "Another option for avoiding the high investment costs associated with new technology is to outsource," explains David Little, DDS, a private practitioner in San Antonio, Texas. "Digital communication enables me to outsource planning and 3D printing, consult virtually with specialists and the patient, and ultimately, create an individualized workflow that best suits my office."

The use of CAD/CAM systems for designing and manufacturing dental appliances and prostheses has been well established, and although the technology itself is not new, it is constantly being tweaked and updated.¹⁶ Other computer-based technologies, including virtual reality simulators and augmented reality, have resulted in new modalities for the instruction and practice of dentistry.¹⁷ For example, the latter is widely used in image-guided surgery, where real and virtual objects need to be composed, integrated, presented, or manipulated simultaneously in a single scene.^18,19 It is also applied in dental implant surgery, maxillofacial surgery, temporomandibular joint motion analysis, and prosthetic surgery.^20,21 In addition, the data obtained from digital radiography, intraoral impression scanners, and CBCT is invaluable when establishing an accurate diagnosis and treatment planning implant cases.

Using these technologies for the proper indications and applications within collaborative workflows is also essential to the overall success of treatment outcomes and patient satisfaction.¹⁰ This is especially true when evaluating and mitigating risk factors that could negatively impact implant-supported restorations.

Technological advancements have improved the treatment planning software and physical materials used for implants, affecting every part of the process. Even before surgery, imaging technology can be used to effectively communicate how treatment will affect a patient's esthetics.

"For me, the big word in implant dentistry is ‘workflow' because it encompasses every step of the process," explains Little. "Being able to seamlessly link all of this new technology makes the placement of implants more predictable and less traumatic and provides you and your office with a systematic, streamlined approach."

Over the years, even the manner in which implant surgical guides are designed and fabricated has been transformed as a result of advances in technology and material processing. Although stereolithography has been a traditionally employed approach to producing implant surgical guides, the invasiveness of the bone-supported stent, potential lack of references, and cost can be problematic.²² Therefore, alternatives that maximize the benefits of treatment planning software, digital imaging, and CAD/CAM manufacturing have been developed to produce noninvasive, precise, tissue-supported guides at less cost.²² "A patient wants what they want. Period. It is my job to explain to them the alternatives," says Bilski.

When a patient's diagnostic information is merged using digital implant treatment planning software, a virtual wax-up can be generated to illustrate where and at what angle implants of a determined length and diameter should be placed, what restorations are needed, and how a patient's smile can be transformed. By combining CBCT and intraoral impression scans, the dimensions of bone and soft tissue can be determined prior to surgery and an individualized surgical guide can be produced for the specific patient. Digitally designed and fabricated using a method of additive processing, such as 3D printing or selective laser melting,¹⁰ these implant surgical guides are essential for determining the precise implant position and the depth of the pilot guides to ensure ideal implant placement. The 3D images enable the evaluation of bone quantity and quality, which is critical to ensure that implants are placed in locations with sufficient high-quality bone.²³ "A CBCT scan is like having a road map, and having a guide fabricated from CBCT data is like having GPS. It is almost guaranteed that we will achieve the position and stability that we planned for," explains Natalie Wong, DDS, president of the American Academy of Implant Dentistry. When compared with conventional techniques, computer-aided implant surgeries can require a substantially larger financial investment but often produce more precise results in addition to allowing everyone involved in the patient treatment plan to collaborate more efficiently.²⁴

Taking this one step further, the use of image-guided robotics to drill the implant site prior to placement has been evaluated in order to achieve greater reliability and more successful outcomes.²³ Studies examining the validity of such methods have found that automated implant placement using image-guided robots is feasible and offers comparable accuracy to other systems for implant insertion.²³ Other research has confirmed the feasibility of using robot-controlled, noncontact, ultrashort pulsed lasers as a means of precisely cutting cortical bone for the preparation of implant sites.²⁵ "Haptic navigation, coupled with AI, will reduce surgical errors and dramatically change the implant industry," explains Sonia Leziy, DDS, a private practitioner in North Vancouver, British Colombia. However, until automated dental implant robotics undergoes more rigorous validation and gains widespread acceptance in the profession, accurate dental implant placement will still more often be achieved using precision surgical guides.

CAD/CAM can be used to create identical replicas of unsalvageable teeth that are ready to be immediately placed on implants as soon as teeth have been extracted.²⁶ "The ‘All on X' technique allows us to extract teeth, and on the same day, place implants and a new set of teeth immediately," explains Wong, "Technology has helped to reduce the healing time as well as improve the entire process and outcome. It is very exciting, but at the same time, there is a lot that can fail if you do not plan appropriately. There is still an inherent risk because the foundation has not set yet. For example, if you broke your arm, you would not play tennis again that same day. Immediately placed and restored implants present a similar situation because the bone still needs time to heal, and we need to be cognizant of that fact."

The process of using intraoral scan data, virtual design, and production without a physical master cast to create monolithic implant crowns connected to prefabricated titanium abutments is now being considered in lieu of conventional manufacturing techniques for posterior implant restorations.¹⁰

Advancements in the materials and techniques are also dramatically changing how dentists and laboratories design, fabricate, and deliver implant-supported restorations.

Ongoing modifications to the surfaces of implants have resulted in improved biologic properties that favor osseointegration (eg, rough surfaces achieve better osseointegration than smooth surfaces).²⁷ The surface roughness of implants has been increased using various methods, including machining, plasma spray coating, grit blasting, acid etching, sandblasting and acid etching, anodizing, and biomimetic coating.²⁸ In animal studies, modification of the implant surface through biomimetic coating has been shown to enhance osseointegration by promoting peri-implant bone formation during the early stages of healing.²⁷ It has also been shown to improve histomorphometric analysis and biomechanical testing results; however, long-term clinical studies in humans are still needed.²⁷

To further improve osseointegration and address some of the issues associated with titanium, manufacturers have developed dental implants made from alternative materials, such as ceramics. High-strength zirconia dental implants can prevent the appearance of peri-implant discoloration among patients with a thin tissue biotype. Although concerns about fracture and removal remain, initial research indicates that zirconia implants can offer a successful esthetic alternative for implant designs, and when compared with titanium implants, zirconia implants exhibit a high level of biocompatibility and are associated with improved osseointegration and a reduction in inflammatory response and the development of biofilm.^29-31 More long-term human studies are needed to fully validate the use of zirconia implants. "Some patients cannot have or do not want to have metal in their mouths, and in these cases, I am using ceramic dental implants," says Sanda Moldovan, DDS, "I always share the pros and cons of the material options with my patients. Although more and more people are choosing ceramic, I am sure to mention that titanium has a longer history; therefore, we know more about what to expect long-term than we do with ceramic."

Zero bone loss is becoming a real possibility for implants. Traditionally, to overcome anatomical limitations and vertical bone deficits in an atrophic alveolar ridge, surgical procedures such as guided bone regeneration, block bone grafting, and maxillary sinus lifts were performed when placing a standard implant.^32,33 In addition to being challenging and potentially dangerous, these procedures are costly and time-consuming.^33,34 "Now, autogenous bone harvesting is required far less frequently," says Leziy. Short implants, often defined as 8 mm or less,^35-37 are considered a simple and effective way to reduce complications, patient discomfort, and procedural costs and times in the rehabilitation of the atrophic alveolar ridge.^33,38,39 However, implants with a length of 8 mm or less should be used with caution because there may be a higher risk of failure when compared with a standard implant.^40,41

The science behind dental implants and their protocols is evolving in exciting ways, making use of cutting-edge materials and technologies. With the currently available technologies for diagnosis, treatment planning, and restoration design and fabrication, it is now possible for dentists to provide predictable implant-supported restorations as a member of a collaborative treatment team. Every aspect of a patient's condition and treatment plan can be obtained, evaluated, manipulated, and shared digitally in order to enhance communication and process workflows. This enables everyone involved to realize greater accuracy and efficiency, which leads to greater implant success rates and, ultimately, to enhanced patient satisfaction.