The continuing success of small-diameter dental implants as a treatment modality has become increasingly clear.^10,^13,^8,^15,^14,⁵ The mini dental implant (MDI) system has provided a cost-effective, time-efficient, patient-satisfying option that can be easily integrated into a general practice. This supports the philosophy that implantology is a science driven primarily by the restorative phase and not the surgical phase. The surgical aspects of implants are a means to an end: the restoration of form and function for the patient. Any implant therapy needs to have the patient’s specific needs addressed in the treatment plan.⁹ What better group to be trained in the placement of implants than the general practitioner who will be doing the final restorations? The number of general practitioners placing implants has increased over the last decade.⁴ Mini dental implants are a minimally invasive treatment option that serve as a rational place for general practitioners to begin their implant experience. The philosophy of a general practice residency is to expose the residents to all areas of dentistry. This provides a springboard from which they can begin to mold their own treatment philosophy. They can acquire proficiency in many areas and still retain the insight into what to refer to specialists. The positive result for our profession of general practice residency training is that more general dentists are trained to treat patients with more complex problems.³ As we see in all areas of dentistry, the general practitioner is seeking further training to achieve a higher level of skill in any given field, and implant dentistry is an increasingly significant part of that learning equation.

The general practice residency at St. Luke’s-Roosevelt Hospital Center in New York city, to illustrate one specific example of this educational trend, is a 1-year postgraduate program with three general practice residents. The hospital also has an Oral and Maxillofacial Surgery residency program. The general practice residents are based in the outpatient clinic of the Roosevelt Hospital Division. They do participate in various rotations throughout the institution, but their main dental clinical experience is at the Roosevelt Division’s outpatient dental clinic. The clinic is a five-chair office with standard equipment in each operatory. The curriculum of the program includes training in the placement and restoration of mini dental implants; specifically the 3M/IMTEC-Sendax Mini Dental Implant System. As a host hospital for training courses, our residents are able to be trained before treating patients with these implants. Early in the academic year the MDIs are introduced. Lecture time is dedicated to information about the placement and restoration of all implants. During the training, the case selection criteria are reviewed for MDIs and conventional implants.

The patients that the residents are encouraged to treat are based on their clinical experience and comfort level with the protocol for these implants. They are highly supervised during the early months of the program and then are encouraged to work independently as the academic year progresses and they have shown competency and gradual proficiency.

The residents are asked to locate a lower lateral or central incisor, single tooth replacement case as their first patient experience. Often these cases are simple with few problems and give the residents the basics they need to treat larger more complex cases. Before treating patients with the MDI, the residents must complete training in the surgical protocol for their placement. This consists of either participating in a one day training course or having the same lecture material presented as part of the regular curriculum during the residency. The goals are for each resident to plan treatments and treat one or more single tooth replacements and one or more implant overdenture cases. There is no limitation on the clinical experience available to the residents in this area.

Curriculum

The curriculum for the placement and restoration of MDIs in the general practice residency program is broken up into three categories: single tooth restoration, complete overdentures, and combination tooth/implant cases. Combination hybrid cases also include crown and bridge salvage cases, which can be rather complicated but nonetheless ideal for the MDI application.

The didactic curriculum includes basic lectures on case selection, surgical protocol, and prosthodontic restoration procedures for MDIs.

After a case is identified by the resident, it is reviewed by the clinical faculty. The proper diagnostics are performed and the implant(s) ordered. The day of the scheduled procedure, consent is obtained, treatment plan is verified, and the resident performs the implant placement with the clinical faculty acting as assistant. The prosthetics are then performed the same way.

MDIs are useful solutions in cases for which conventional implants are not possible, either due to prosthetic restrictions, surgical restrictions, or medical restrictions. The dental clinic in a hospital setting treats a large medically compromised population. Often hospital clinics treat a financially compromised population as well. These two parameters combine to make the ideal patient population for the use of the MDI in both fixed and removable restorations. The initial training in oral implantology needs to begin with complete diagnosis. It is the foundation for the success of any procedure. The criteria for MDIs as well as for conventional diameter implants are taught and clearly understood by the residents. This allows them to properly identify patients who may benefit from MDIs or whose restorative needs would be better met with larger diameter, conventional implants. Patients who might also be candidates for a conventional implant approach are typically referred to the Oral and Maxillofacial Surgery residents for treatment, and then they return for restoration. Recently the placement of MDIs has also been introduced into the oral surgery teaching curriculum, but currently only general practice residents are placing and restoring them.

Medically compromised patients who have all of their care, including dental care, in hospital outpatient clinics tend to have a number of complex medical issues and comorbidities. These are the same conditions that would preclude them from being able to safely tolerate invasive dental surgical procedures without increased medical risks. Conventional dental implant surgery is often in this category. With the use of the MDIs for these patients, we can provide them the life quality improvements that come with implant enhancement of existing prosthetics. The minimally invasive surgical protocol for the MDIs assure decreased stress during placement, during restoration, and minimal to no discomfort during recovery.

Resident Case Selection

When selecting a first MDI case for restoration, the residents are encouraged to limit as many variables as possible. As their experience and training progress, more complicated patient profiles and procedures are selected. Hospital dental clinics fabricate a large number of complete dentures. This is usually due to the patient populations’ financial limitations and dental history. For the same reasons, these patients are usually not offered or, if offered, able to accept conventional dental implants. Others have avoided anything but dentures due to fear of surgery, fear of pain, or, again, for lack of finances. Moreover many of the patients are kept from surgical implant therapy by their medical status. Often consultations from cardiology, hematology, and many other medical specialties advise against invasive procedures on certain patients. These cases are where MDIs shine as an option. As a first case, the residents are asked to select patients with few complicating medical conditions (ASA 1 to ASA 2) (Box 5-1).²

BOX 5-1 American Society of Anesthesiology (ASA) Physical Status Classification System

ASA 1: a normal healthy patient

ASA 2: a patient with mild systemic disease

ASA 3: a patient with severe systemic disease

ASA 4: a patient with severe systemic disease that is a constant threat to life

ASA 5: a moribund patient who is not expected to survive without the procedure

ASA 6: a brain dead patient whose organs are being harvested for donation purposes

Our patient population is vast and diverse. Any hospital service will draw patients from within the institution as well as from the community. The patients are varied both medically and socioeconomically. Over time we have become a center for small diameter implants, with regard to both their placement and their restoration. For the purposes of this chapter, we will focus on the medical and dental parameters of our patients. We are faced daily with many different situations that require a complete understanding of the patient’s past medical history and how it will affect the proposed treatment plan.

Patients With Medical Complexities

A multitude of our patients are referred from neighboring medical clinics. The use of hospital outpatient clinics for primary care medicine will benefit a patient because all of their primary care and specialty care is under one roof. This allows and encourages better coordination of therapy and communication between the various medical and dental practitioners. Many of our regular patients will fall into the ASA 2 category. These people have one or more medical conditions that are well controlled by lifestyle, diet, and/or medications. These patients are to be treated with a clear understanding that as long as their medical conditions are managed well, and they are in “control,” they have low risk for complications from either small diameter minimally invasive procedures or conventional larger diameter implant placement surgeries. As we look at more complex medical histories in our patients, extensive surgical procedures such as might be needed in some cases for multiple conventional implant placement may put them at risk for greater postsurgical complications.

Patients With Cardiac Conditions

The hospital dental clinic setting is a common place for referrals of patients seen for other services in the hospital. Many patients have some form of cardiovascular disease. Arteriosclerosis and hypertension make up 40% of all organic heart diseases.⁹ Recent protocols for patients in cardiac rehabilitation who have medication releasing stents dictate that they must stay on oral anticoagulants for the rest of their lives. In some cases, these patients are treated with a combination of anticoagulant and antiplatelet therapies.¹² These patients are at risk during surgical procedures for excessive bleeding. They are at times poor candidates for large incisions and flap reflections. Due to the vascularity, cutting osteotomies into medullary bone causes bleeding. Increasing the diameter of the osteotomy opens more vasculature to increase bleeding. Wide full thickness mucoperiosteal flaps causes bleeding as well. Both procedures can cause changes in crestal bone that can adversely affect implant healing.^9,¹¹ A far better option for this group of patients is the simplified nonsurgical protocol of the MDI. Because no flap is created, bleeding is minimal. The hole through the soft tissue made by the pilot drill is only 1.1-mm wide. The pilot hole is taken one-third the length of the implant (in moderately dense bone) and removed. The implant is then placed into the hole and engages bone. As the implant is progressed to full length, it is not removing bone as an osteotomy would, but rather compressing the bone around it. This tamponade stops medullary vessels from bleeding. This also contributes to its initial stabilization. This generally stops any bleeding from bone, and the procedure is completed with little or no postoperative bleeding.

Patients After Radiation Therapy

Another common referral to our dental clinic is from the departments of Medical and Radiation Oncology. These patients often present after surviving various forms of cancer and having had radiation and chemotherapy. The bone and soft tissue will be affected directly. The associated medical issues and compromised immune system place them in a fragile category in which conventional implant therapy to replace missing teeth or to stabilize a removable prosthesis is not an option. Radiation therapy has much longer lasting consequences that chemotherapy. Patients who have had radiation therapy directly to the mandible or maxilla due to oral and head and neck cancers or metastasis to the head and neck region are particularly fragile. These patients are often faced with few options for improvement of quality of life in the area of their oral health, both in form and function.⁶ Often radiation to the head and neck results in destruction of the salivary glands, both major and minor. Complete denture retention relies heavily on oral moisture to develop “suction.” Without this moisture denture retention suffers and denture function is severely impaired. With the concurrent loss of stability, denture sores are common and heal poorly due to decreased tissue vascularity. The minimally invasive protocols for MDIs are again of great benefit in these cases. Using the MDI to stabilize complete upper and lower dentures gives these patients the ability to function with their dentures normally.

For patients who have received radiation therapy to the mandible or maxilla, conventional implants would not be an option. The process of healing relies on the formation of a stable clot from healthy bleeding bone. Higher doses of radiation therapy decreases the ability of bone to heal properly. Radiation therapy also results in compromised vascularity of the overlying, soft tissue. Large, full thickness flaps show poor healing and are at risk for breakdown, exposing underlying bone. The margins of a surgical flap and the cut bone walls of a conventional osteotomy will have poor healing. The MDIs are placed into the pilot hole, and they are self threading and compress the bone as they engage it. After the pilot hole there is no cutting of bone when using the MDIs, and the compromised vascularity will not adversely affect the healing.¹

Patients After Chemotherapy

Many types of cancer are treated with a combination of radiation and chemotherapy. Although radiation therapy may not affect the prospective implant surgical sites, if chemotherapy is used in conjunction to treat the cancer, the systemic effect is a concern. The severe neutropenia that accompanies chemotherapy places a patient at much greater risk for postoperative complications. The best option of course is to wait a prescribed amount of time before beginning any elective dental surgery. The healing of the soft tissue, response of bone to surgical trauma, and the risk for infection will benefit from waiting.⁷

Patients With Developmental Disabilities

In a large segment of the developmentally disabled population, the only treatment for advanced caries is extraction. As one would expect, this would leave a large portion of that population either partially or completely edentulous. To further complicate dental rehabilitation, there are often advanced medical conditions and multiple medications for both systemic disease and emotional or psychological support. The range of developmental disabilities is vast. Any combination of symptoms can lead to any number of issues regarding a patient’s ability to function.

In many cases these patients are treated in a routine dental setting for restorative procedures, but for any more invasive procedures such as oral surgery, soft tissue surgery, or even implants, general anesthesia is indicated.

Patients who cannot tolerate dental care in a routine setting will benefit from general anesthesia. In some cases, the outcomes will be better than if only conscious sedation is used. After these patients have any unrestorable teeth removed, they are left partially or completely edentulous. That leads to the next great challenge of restoring the patient to function with prosthetics. Often fixed prosthetics involving castings and porcelain are not practical due to the rather technique-sensitive nature of tooth preparation and impression making and a patient’s inability to sit and tolerate such procedures. Often a sufficient impression for an acrylic removable prosthesis is all that is possible. Fabrications of all-acrylic removable prostheses are therefore often easier for both the patient and practitioner. The next challenge lies in the patient’s ability to retain and then function with these prosthetics. MDIs greatly increase the success of these prostheses by increasing retention and stability. Once again, the simple and minimally invasive nonsurgical protocol for MDIs makes them the solution of choice. After the prosthesis is fabricated, a return to general anesthesia or sedation will allow the placement and attachment of the implants to the prosthesis. This allows a patient immediate ability to function with the prosthesis, without waiting for surgical healing and a third visit under anesthesia.

In this same vein, because there are fewer postoperative complications with these implants, the postoperative problems that are much harder to manage in these cases can be avoided.

If a patient presents with a small edentulous area a greater number of implants can be placed and used to retain a fixed prosthesis. The nonsurgical protocol lends itself to the treatment of patients for whom a larger more invasive and longer implant surgery is not ideal. In these cases, a laboratory processed long-term provisional bridge is the restoration of choice. A processed temporary is serviceable for repair or modification, can be removed if needed for evaluation, and replaced at reasonable cost.

Clinical Applications

It is best to examine the clinical applications of small diameter implants by looking at their various applications separately. The remainder of the chapter will be looking first at removable applications in various types of patients, then the uses for fixed prosthetics, and finally salvage operations of fixed prosthetics.

The place to begin in the review of the versatile uses of the small diameter MDI is with the most exciting solution for a patient with a complete lower denture: overdenture support. As any lower denture wearer will willingly share with anyone who asks, a lower denture does not stay still during function. Even the best fitting, properly extended, and well maintained lower denture will move during function. Upper dentures are to some degree better in terms of retention due to the support of the full palatal coverage. During function, however, both dentures will dislodge and move. The classic prosthetic adage “enter bolus, exit balance” clearly defines the reality that dentures at rest and in occlusion do not move, but during function they move readily.

With the advance of implant dentistry, overdentures retained in place with various types of fixtures have become standard. Their benefit however has not become universally accepted due to obstacles to many patients. Some of these obstacles are cost, fear, lack of understanding (by both patients and dentists), and the inability for the patient to have the implants placed due to medical, surgical, or anatomic limitations. MDIs have been able to overcome many of these obstacles for many patients, taking dentistry one step closer to making implant-supported overdentures the standard of care.

It is important to remember that regardless of the simplicity of placement and use of small diameter implants, they require the same preparation, both diagnostically and in patient preparation. The preoperative workup of a potential patient needs to adhere to the current standards.

Patient Interview

Any patient who is being interviewed and who is seeking implant dentistry needs to completely understand their options. A review of expectations and final treatment goals need to be done to assure that they can be met. Some of the most successful cases could be considered failures if patients’ expectations are not met. A complete informed consent covering all implant options and restorative options must be done. It is during this process that the benefits of small diameter implants will be clear. In some cases, a patient’s needs and restorative goals may not be suited for MDIs, and either conventional implants or even a combination of MDIs and conventional diameter implants may be appropriate. It is recommended that a written consent form is provided to the patient that reviews the details of the discussion. The patient should be allowed to review the document and initial each specific paragraph and sign at the end. The treating dentist and a witness, usually a dental assistant, should also sign the consent.

Radiographic Studies

Radiographic studies of the proposed implant sites will provide the basic information needed to plan the placement and help in the selection of the proper implant type and length. A combination of panoramic and periapical radiographs will provide a clear indication of a patient’s oral maxillofacial anatomy and dental anatomy.

In most cases, CT scans are not needed. In cases where the anatomy is unclear, or space for implants is very limited, these higher level studies can be useful. With the advent of cone beam tomography, a comprehensive 3D image can be constructed to allow clear diagnostics in the selection of the implant and placement.

With the panoramic and periapical radiographs mounted properly, a clear overlay template can be used to visualize what various implants will look like after placement. Issues of angulations, depth, even implant diameter can be decided.

Other critical diagnostic information can be determined by close inspection of the radiographs. Mainly, anatomical landmarks and possible limitations to implant placement can be visualized. In some cases the quality of the bone at the implant site can be assessed before placement from the appearance of the bony architecture on radiographs. Of course the overall health of the bone is evaluated to assure there are no lesions, malignancies, or other pathologies present.

In most cases, the main anatomical structures that must be identified on radiographs and subsequently avoided during placement are the anterior loop (Figures 5-1 and 5-2), the inferior alveolar canal (Figure 5-3), the mental foramen and the floor of the nose (Figure 5-4), and the floor of the maxillary sinus (see Figure 5-3). There are occasions when engaging the floor of the maxillary sinus is beneficial, resulting in bicortical stabilization and enhanced initial stability of the implant. Radiographic examples of this bicortical stabilization can be seen in Figures 5-5 and 5-6.