Introduction:

Evidence-Based Implant Dentistry (EBM) constitutes a new approach to clinical practice in which clinical decisions derive from the integration of the doctor’s experience with the conscientious, explicit and judicious use of the best scientific evidence available, all of this mediated by the preferences of the patient”.
Good EBM practice articulates in four steps:

  • Formulating a question means to translate a clinical doubt into a searchable question format.
    Getting the evidence involves the knowledge of all the instruments available to answer the
    original question.
  • Appraising the evidence means to possess the instruments to critically analyze the available scientifi c literature.
  • Applying the evidence is the process by which the collected evidence is applied to a specific clinical scenario.
  • The defi nition of best scientifi c evidence by itself may generate some confusion. It can be defi ned as the information derived from a properly conducted research or study aimed at proving or countering a scientifi c hypothesis.

Teeth or Implants ?

One of the main challenges for the modern implantologist is to resolve the clinical dilemma about whether to extract or retain a tooth. At this regard, evidence-based decisions are based on the concepts of survival, success, and failure. Comparison of implant solutions with endodontic treatment needs a separate analysis between primary endodontic procedures, re-interventions, and endodontic surgical options. Comparison with fixed prosthesis on natural abutments is best made analyzing separately the success and failure of single crowns and multipleunit restorations.

Patients with missing teeth or damaged dentition can undergo different restorative procedures or tooth extraction followed by implant placement. In order to provide the highest level of care, the clinician must take into account the individual needs and preferences of the patient but also the pros and cons of a given approach. Treatment decisions after evaluation of a traumatized tooth are based on clinical and radiographic fi ndings. When possible, every effort should be made to preserve pulp vitality in order to ensure a positive long-term prognosis. A successful implant treatment presupposes an effective osseointegration, which is the direct apposition of bone to the implant surface. The implant surface plays a major role in the bone response leading to osseointegration. For this reason, evaluation of chemical and physical characteristics is considered important in order to choose the best implant and obtain optimal
clinical results.

Implant Placement and Loading Time

The knowledge of the physiologic mechanisms of socket resorption after extraction allows to reliably place an immediate implant. Moreover, in the majority of the situations, immediate placement and loading can give esthetic outcomes comparable to conventional protocols. Also, immediate placement in previously infected sockets may be possible after accurate debridement and antibiotic use. Regarding the loading time, early or immediate protocols seem to give comparable results to the conventional ones.
Conventional ( delayed ) placement any implant inserted at least 2 months after tooth extraction
Conventional ( delayed ) loading any implantsupported prosthesis loaded at least 2 months after implant placement
Immediate implant placement any implant placed in fresh extraction sockets after tooth extraction
Immediate loading any implant-supported prosthesis loaded earlier than 1 week subsequent to implant placement
Early placement any implant placed in healing extraction sockets within 1 week and 2 months after extraction
Early loading any implant-supported prosthesis loaded between 1 week and 2 months following implant placement.

Implant Design and Implant Length

Implant Design is a fundamental aspect of successful implant treatment. Improvements in implant design and its composition has prompted change of selection criteria for different clinical scenarios, an example being the use of short implants to avoid the need of advanced bone grafting techniques. Dental implants are unique when compared to other implantable devices in the human body, as its design has to take into account that it is additionally connected to a prosthesis which is exposed to the oral cavity and therefore subject to two environments. This prosthetic interface on the implant body, where the implant abutment connects, can either be external or internal in nature.

Implant design can be classified broadly into macro- and microstructural features. Macro- design features include body shape, threads, anti- rotational features, and thread design (pitch, depth, angle, thickness, thread helix), while micro-design features comprise surface topography, material composition, and bioactive coatings. Most evolution in implant design is centered on the modifi cations of these features to achieve: high levels of primary stability, faster and better quality osseointegration, reduced peri-implant bone loss, and improved stress distribution during functional loading.

Implant Materials

Currently the vast majority of implants are made with commercial pure titanium or its alloys, with a small percentage being hydroxyapatite-coated titanium, zirconia, or zirconia alloy. Titanium and its alloys have a proven track record as the material of choice for implant fabrication, given its biocompatibility and mechanical properties.

Platform Design

Implant platform is defined as the portion of the implant on which the abutment rests. Platform-switching design uses an abutment that is smaller in diameter than the outer edge of the implant neck. This particular design has been found to be associated with reduced marginal bone loss. It remains to be established if this favorable outcome occurs in all the clinical situations and with which extent. Possible factors that seem to contribute to the preservation of marginal bone in platform-switched implants are the shifting of the microbial leakage far from the bone or of the abutmentplatform micromotion. Other cofactors may also contribute. Scalloped implant design is a new platform solution indicated in the esthetic zones, but although promising, more clinical studies are needed to confi rm its validity.

Implant Abutments

Abutments are important for the success of the implant treatment. The abutment screw is an important component that serves to secure the abutment to the implant. The preload, depending by the torque, is the initial load and elongation of the screw that is important for optimal holding of the components together. An optimal preload is a prerequisite for preventing screw-related complications such as screw loosening and stripping. Regarding the types of connections, when internal versus external typologies are compared, it seems that internal connection gives best
results in terms of lower rate of complications. Finally, the use of angled implant abutments is necessary in some situations, which increases the stress around the peri-implant bone at the same time does not seem to impair the clinical results. Computer-aided design and computer-aided manufacturing (CAD/CAM) is a technology that has
been available in prosthetic and implant dentistry for at least two decades. Continuous improvement have rendered possible to think about a routine use of this technology in the everyday practice.

Implant Prosthodontics

Retention systems for implant prostheses can be obtained via screw retaining or through cementation.
These two options gave distinct advantages and disadvantages in clinical practice, but doubts still exist if the choice of a retention system over another can give some improvement in terms of success and survival rates.
In selected cases, advanced treatment options are necessary. It is the case of zygomatic implants, which are useful when more traditional approaches are unfeasible. Considering the delicate structures involved and the surgical skills required, placement and restoration of zygoma implants should be performed in adequate structures by properly trained clinicians.
The All-on-Four TM is a prosthetic concept which employs four implants in the anterior jaw, of which the distal two are maximally angulated. The sparse evidence coming from the literature suggests that this can be a reliable
option in selected cases.

Pre-Implant Reconstructive Surgery

For different reasons, soft and hard tissues do not present an adequate volume that is required to achieve an ideal situation to ensure the survival, function, and aesthetics of our implants. To solve these problems, bone grafting procedures may be indicated in order to prepare the site in advance or sometimes at the time of implant surgery. When the alveolar ridges lack appropriate volume, reconstructive surgery is needed. Several surgical techniques and bone grafting materials are available for that purpose. For that, the surgeon needs a critical evaluation of all these techniques and biomaterials to be able to select the most appropriate procedure and graft type. The ultimate aim of the surgeon is to maximize success and minimize morbidity.

The use of bone grafts in the repair of defects in dentistry has a long history of success, primarily with the use of autogenous bone. There is an increase in the demand for reconstructive surgery and thus bone substitutes, principally due to the increase in life expectancy, changes in the lifestyles with expectation of a good life quality, and the wide acceptance of minimally invasive surgery.
Many techniques exist for effective bone augmentation. The approach largely is dependent on the extent of the defect and specific procedures to be performed for the implant reconstruction. It is most appropriate to use an evidenced-based approach when a treatment plan is being developed for bone augmentation cases. The capacity of bone grafts to restore original bone volume varies, and the results reported in the literature are contradictory due to differences in observation periods, type and site of reconstruction, timing of implant loading, and, last but not least, site of bone harvesting. A second concern is the adequate adaptation, stabilization, and vascularization of the bone graft, which are critical for graft success.

Peri-implantitis

Peri-implant infl ammatory conditions are not unfrequent in the implant population. The etiology of peri-implant diseases has many aspects in common with periodontitis, although some etiologic aspects are peculiar to the first one. Microbiological factors, inflammation, smoking, diabetes, and genetic factors are all considered risk factors for the development of mucositis and peri-implantitis.
At the current state, it seems that prevention is the best way to face peri-implant diseases. Careful patient selection allows to avoid the implant treatment in those patients predisposed to the development of peri-implantitis, poor oral hygiene and cigarette smoking being the most important risk factors. After implant placement, a lifelong follow-up with regular checkups is mandatory in order to reduce the incidence of peri-implantitis.