Dental implants have emerged as the standard of care for replacing a single tooth in healthy patients. In the US alone more than 35 million Americans are edentulous and 178 million are missing at least one tooth. 1According to the Levin group it is estimated that the number of dental implants received by patients will increase by 500,000 each year, almost 10% annually. 2
An iData™ search will show that dental implants are now a 1.4 billion dollar industry and growing rapidly. The recent surge in implant dentistry can be directly associated with the reduction in product cost. As the cost of dental implants have declined and the tools and skill sets have improved, more and more patients are receiving dental implants as the permanent solution to their missing teeth. In 2015 general dentists (GPs) in the US placed the same number of implants as specialists. That number looks to be swinging in the direction of the GP.
The fear of dental specialists has always been that GPs are not trained well enough to treat the problems that come with placing dental implants. That fear was not so farfetched. As a GP myself I’ve seen and treated many cases from specialists and GPs alike that have encountered peri-implant disease. It seems that a new specialty will arise to combat these peri-implant defects. A sub-specialty, if you will, that I would like to coin –“Peri-implantologist”.
Peri-implantitis as defined by the American Academy of Periodontics is an infectious disease that causes an inflammatory process in the soft and hard tissues surrounding an osseointegrated implant, leading to the loss of supporting bone. The treatment of this disease has become a hot topic for discussion. It seems that at almost every conference I attend, and I attend many, there is at least one presenter discussing this topic.
There is a running joke in the dental community that when you put 3 dentists in a room and request a treatment plan you’ll get 9 different answers. There are often different treatments in dentistry that can yield similar results. This disease is no exception. Non-surgical treatments, including mechanical debridement, localized and/or systemic anti-microbial therapy and the use of dental laser therapy have been researched and employed. In addition, surgical intervention with the use of detoxifying agents, bone augmentation, polishing or removing implant threads, soft tissue augmentation and more have been used. All these treatments are still undergoing long-term studies. To date there is no clear consensus on how to treat these cases.
The key to preventing any problem is to understand the situation from which it arose. As our study and understanding of dental implantology continues to improve, guidelines have been developed and continue to be developed. While there are many factors that contribute to peri-implant disease, this article aims to tackle just a few. We will discuss seven key factors that must be addressed to improve clinical outcomes.
As dentists we always focus on periodontal health. As physicians we must expand our scope of interest to include the overall health of the patient. It is widely accepted that patients that are considered unhealthy should not receive a dental implant since placing a dental implant is considered an elective surgery. There are always other ways to treat patients. A dental implant is just one of the treatment modalities we can consider for our patients. Cardiovascular, pulmonary, endocrinological, or psychological conditions must be taken into account, for the well being of our patients. The patient with uncontrolled diabetes is an example of a patient to treat with caution.
Patients on bisphosphonates are a big topic for concern, as increased indications for bisphosphonate use have developed. Even male patients may be receiving these drugs for cancer related treatment. 3 The intravenous form is of greater concern than the oral form. 4 Be aware that new studies are showing increased half-lives for these drugs. 5 Discussions with the patient’s physician may be required as a prerequisite for surgery.
New research has found the correlation of high cholesterol and low vitamin D levels as potential contributors to peri-implant disease. While otherwise considered healthy, these patients exceed or are deficient in substances the body requires for proper healing. See Tables 1 and 2 for appropriate values of these substances.
Residual sub-gingival dental cement was associated with signs of peri-implant disease in a vast majority (81%) of the cemented cases in recent studies. 6,7 The preferred method of restoration for peri-implant health is the screw-retained prosthesis as it doesn’t involve the use of dental cements (Fig. 1). However, the screw-retained prosthesis is not always possible. Many users prefer cement for larger cases. Newer radiopaque cements have emerged on the market. These cements allow the practitioner to observe cement tags on radiographs in two dimensions and thereby, hopefully, prevent cementitis (Fig. 2).
Uses of barriers such as teflon, rubber dams and gingival protective cuffs have allowed for a safer use of these cements (Fig. 3). Since there are many types of cement available, it is recommended to check the current cements you use in your practice and investigate if they are in fact radio-opaque. The damage that can be caused by residual cements can become catastrophic to the survival of the implant (Fig. 4). If left untreated, implant explantation may be required.
Screw-retained crown eliminating the need for cement.
Radio-opaque cement visible on 2D radiograph.
Gingival protective cuffs preventing the submergence of excess cement into the gingival sulcus. This allows for the simplified removal of cement.
Effect of excess cement leading to circumferential bone loss around the dental implant.
The Bone sets the Tone
We know after many years of research that the minimum thickness of bone required for a dental implant to survive should be greater than 2mm. 8,9The body will continue to remodel until this ratio is met. Recent technology has led to some remarkable devices to enable the clinician to recreate the proper thickness of the buccal plate. The use of customized titanium implant retained membranes burst onto the implant stage four years ago. They have been used extensively to recreate lost osseous structure while the implant is in its various stages of integration (Fig. 5).
Understanding the minimum required distance between the implant and natural tooth (1.5mm) and the implant to implant (3mm) is critical to the long-term health of both the osseous and gingival tissues. These measurements must be respected in planning and placement. Violating these measurements can often lead to interproximal tissue loss. This loss of papillary height can often create unsightly black triangles. This can be catastrophic in an area of aesthetic concern even with the use of gingival porcelain masking.
Customized titanium implant retained membrane. Note the design allows for predictable bone growth beneath the titanium mesh.
The Tissue is the Issue
Gingival architecture is paramount to the success of the fixture. Once adequate osseous structure is obtained, the development of the soft tissues becomes significant. Several studies have pointed to the importance of keratinized tissue with respect to its quality and quantity. 10,11,12 There are several techniques to enhance the soft tissues and increase its keratinization. When the appropriate amount of keratinized tissue is present coronally, apically repositioned flaps can allow a concavity in the soft tissue to become a convexity without the use of any membranes or biologics (Fig. 6).
In the absence of keratinized tissue, sub-epithelial connective tissue (Fig. 7)and free gingival (Fig. 8) harvesting and grafting can replenish the much-needed fibrotic tissues. Once healing is complete, the tissue can properly defend itself from the harsh oral environment. While not always indicated, allograft materials can be used in place of these autogenous tissues. Their use eliminates the necessity for a donor site reducing secondary site morbidity. 11,12
Apically repositioned flap. The thicker keratinized tissue was advanced apically to create proper soft tissue contouring.
Autogenous sub-epithelial connective tissue harvested from the palate is placed around a deficient implant. Note increase in keratinization.
Autogenous free gingival graft. Note the absence of keratinized tissue prior to surgery. A resultant band of thick healthy tissue develops following the graft.
Cone Beam Computerized tomography
Cone-beam computer technology, or CBCT, has helped revolutionize dental care. CBCT is used widely for treatment planning and diagnosis in implant dentistry. This technology has proven helpful for oral surgery, endodontics and orthodontics. 13 In the past, bone sounding with probes, along with 2D X-rays was the only way to deduce the topography of the bone. This provided little information to the clinician with regards to anatomical variations and concerns. Utilizing the CBCT, the clinician can diagnose the area of treatment more effectively. This minimizes the risks that go along with surgery. 14
The affordability and more compact designs of the newer CBCTs have allowed even the smallest practice to adopt this technology. Indeed, the 3D technology has made reviewing treatment plans with patients much easier. The reconstruction of the arches (Fig. 9) gives patients the ability to visualize the pathology. Patients are more willing to accept treatment plans as a result. The capacity to render a three-dimensional reconstruction of the mouth and the ability to see the voids caused by infection, have resulted in an increase in case-acceptance rates as well as a reduction in surgical complications.
Premature Implant Loading
When is the proper time to restore a dental implant? In the past clinicians relied on arbitrary dates, tapping sounds, or less conservative methods of reverse torquing. Over the past 10 years, Ostell™ has developed a library of data to eliminate the questions regarding loading times. 15 Through the use of resonance frequency analysis, a magnetic smart peg (Fig. 10) is secured to the implant body. 16,17,18 The unit delivers a numerical value that correlates to the micro mobility of the implant (Fig. 11). This value is termed ISQ–implant stability quotient. 16 Studies have shown that forces exceeding 200N (or 20.4kgf) can cause enough micro movement to prevent osseointegration and induce fibrous encapsulation of the fixture body. 17Determining the ISQ value enables the clinician to decide when to immediate load, when to delay loading and even to diagnose an unsuccessful integration prior to delivery of the prosthesis. If we can accurately determine when to load the implant we reduce the chances of fibrous encapsulation. This reduces the chance of peri-implantitis due to premature loading.
Ostell™ smart peg.
Reading from Mega ISQ by Megagen™.
The final topic I’d like to discuss involves the choice of implant design. The newer developed implants have overcome many of our previous difficulties. Screw loosening, micro-gaps, implant or screw fractures are some of the difficulties the can now be avoided. And improved surface technology enhances clinical outcomes. Perhaps the biggest innovation has been in the platform switching of the implant-abutment interface. This concept involves the reduction of the restorative abutment diameter with respect to the diameter of dental implant (Fig. 12). Long-term studies have concluded higher levels of bone preservation around platform switched implant-abutment connections. 18,19,20 The reduction in the diameter of the abutment allows the peri-implant mucosa to fill in the space (Fig. 13). The resulting tissues become thicker, preventing contaminants from invading the peri-implant tissues and keeping the tissues healthier.
Manufactures have begun to include a narrow platform on the fixture and a wider thread design apical to the connection. This has a positive effect in preserving the crestal bone since we do not remove the bone where it is needed most (Fig. 14). The reduction in the core diameters of these implants and the thread position enables the clinician to preserve osseous structure and often reduces the need for augmentation.
Dual platform shift design of Megagen any ridge implant system™. The red line represents the initial platform switch at the abutment-implant connection. The blue line represents the 2nd switch built into the neck of the implant eliminating the need for removal of excessive crestal bone.
Radiograph depicting dual switch design. Red arrow – 1st platform switch. Green arrow – 2nd platform switch.
Example of a narrow ridge preserved crestal bone by using a 2nd platform switch.
We are entering the next generation of implantology. We must accept the fact that even when all criteria for success are met, complications and failure can still occur. We are treating the human body. As a result, we are subject to its changes and will. Therefore, peri-implant disease will be difficult to eliminate in its entirety. However, if we can reduce the number of factors that directly affect its causality than perhaps we can reduce its occurrences in our clinical practices. Continuing our education will always remain the most effective way to combat the complications in our practices.