Mini Implants in Dentistry: An Overview

Introduction

Dental implants are the gold standard for replacing missing teeth, in comparison to other prosthetic modalities like a crown, bridge, or removable dentures. Currently, dental mini implants have also been setting a new age trend in implant dentistry, touted for being an economic or budget-friendly alternative to dental implant placement by dental operators. However, mini implants are a technique-sensitive task to be performed by the dentist and may have several disadvantages compared to conventional dental implants.

The mini dental implant system is very similar to the dental implant system. However, according to dental researchers, it only utilizes the technology of a self-tapping threaded screw design that can allow for effective gingival (concerning gums) and peri-implant tissue (soft tissue) health. The mini implants are usually placed only by incorporating a minimally invasive surgical intervention modality. For successful osseointegration (a functional connection between living bone and the surface of a load-bearing artificial implant) of the mini implants into the jaw bone and for optimizing maximal or higher success rates postoperatively, the implant dentist needs to verify the initial stability of the mini implant within the bone.

What Are the Indications of Mini Implants?

Here are some of the common situations in dentistry where edentulous patients would be needing Mini implants:

1. Edentulous individuals who prefer an alternative prosthetic option for complete dentures.

2. Individuals who cannot afford the increased cost of standard care and the cost of standard or conventional dental implants.

3. In economically disadvantaged patients who are indicated for getting their maxillofacial prosthesis within a specific budget range.

4. In medically or immunocompromised patients who may not be good candidates for surgical procedures before conventional dental implants.

5. In patients where ridge augmentation procedures cannot be performed because of local infection or risk factors for conventional dental implants.

What Are the Factors Influencing Mini Implant Success?

The given below factors are considered by implant specialists that mainly influence the clinical and long-term success outcomes of mini implants:

• Design of the Mini Implant: This is done by the operator who will select or design the correct mini implant shape, thread patterns, and the surface modification or treatments to be performed before dental mini implantation, for enhancing primary stability and faster osseointegration or bone implant fusion of the mini implants in the jaw.

• Size of Mini-Implant: This is a crucial factor that affects the retention area and is a major determinant of osseointegration.

• Patient's Individual Occlusion and Masticatory Forces: These are preoperative factors that should be thoroughly evaluated by the implant dentist and can influence mini-implant success.

• Number and Position of Mini-Implants to Be Placed: The exact location as well as the number of units needed to bear the masticatory forces of the upper or lower jaw is a major determinant of long-term mini implant survival outcomes.

• Mini Implant Length and Diameter: The selection of a mini implant by the dentist is based upon the diameter and length of the mini implant, because the stress distribution along with the load direction is a crucial factor for distributing even forces of mastication in the jaw, across the body of the mini implants.

What Surgical Assessments, Techniques, and Cautions Are Needed for a Mini Implant?

1. Surgical assessments: The technique for mini implantation usually incorporates preoperative planning by the maxillofacial surgeon or dental implantologist in detail, which will include a maximum amount of diagnostic information about the patient, as needed. A panoramic X-ray or an OPG (orthopantogram) is a minimum requirement for preoperative assessment of mini implants, while a cone beam (CT) scan in contrast is the 3D imaging technology or radiographic modality that is the most recommended by implant dentists for 3D planning. CBCT (cone beam computed technology) technology or radiographic imaging would also be useful in dental patients with narrow atrophic ridges.

2. Techniques: The next consideration that would be important for the implant dentist is whether to raise a flap or do a flapless surgery. Usually, If there is sufficient ridge width, then a flapless trans gingival technique would be adopted using the pilot drill initially. In cases, however, where there is a narrow ridge comprising extensive soft tissues, a minimal flap design using a crestal incision will be performed by a dentist to reveal the underlying jaw bone. This crestal incision would allow the implant dentist to locate the exact area of dental implantation or allow for placement of the implants just at the correct angulation within the jaw bone.

3. Cautions:

• Any prosthetic failure that pertains to mini implant-supported maxillary (upper or mandibular (lower jaw) removable prosthesis would usually be attributed to:

  • An incorrect facial angulation of the implants.

  • An operator-based error that would result in a lack of primary stability of the implant, resulting in eventual failure.

• In the cases of maxillary mini implants, patients usually require thick soft tissue to deal with the masticatory forces exerted on the teeth of the upper jaw or the maxilla. Hence, the dental implantologist usually plans a longer implant abutment (a critical component in both dental and orthopedic applications, serving as a connector or support structure between an implant and a prosthetic device) with the right minimal insertion torque of around 35 Newton per centimeter during the time of mini dental implantation using a ratchet. When the implant dentist torques the implant right, it would be indeed one of the defining factors of the primary stability of the dental implant. The higher the primary stability, the better the survival rates and lack of any micromovements (which otherwise can lead to any prosthetic failure).

• Biological complications that are associated with mini implant failure include the common complications of peri-implantitis/ progressive bone loss, peri mucositis (an inflammatory condition that affects the soft tissues surrounding a dental implant, without affecting the bone supporting the implant), periapical implants, or even any possible sensory disturbances encountered in the jaw.

• Care should be taken by the dental implant specialists to ensure that the patient's cortical bone should not be thinner than 0.5 millimeters and the density of trabecular bone as well should not be low. If the cortical bone is too thin or the trabecular bone density is quite low at the area of implantation, mini implants indeed have a high chance of prosthetic failure. Such patients should hence, be preoperatively assessed and if they are in the exclusion criterion for dental mini implants, then patients should be informed about the same instead of risking short-term or long-term prosthetic failure.

Conclusion

Mini implants can be good alternatives to implants when the bone space in the jaw is compromised. The primary stability of the mini implants would be poor when pre-operative assessment is lacking on behalf of the dental operator or implantologist. As one knows the primary stability of a dental implant is the most important factor that influences it in terms of long-term outcomes and survival rates. Therefore the dentist should decipher or analyze the patient's bone quality through preoperative assessment for implant design as well as for the choice of surgical technique that would be used.