Prosthetic devices are often used as surrogates for missing skeletal and dental elements. These devices are in close contact with the surrounding tissues, and their functionality and stability are critically dependent on the successful integration within the tissue’s extracellular matrix (ECM). The surface of the implanted device directly interacts with cell and extracellular milieu and influences their biological activities affecting the healing of the implant site after the surgery, tissue regeneration, and the formation of an organic interface with cells and ECM proteins.

Dental implants are commonly used to replace missing teeth, and the long-term success of these implants depends on their proper integration with the mineralized bone, a process commonly known as osseointegration.

It has been a long-standing challenge to achieve successful osseointegration of implants in older population with poor bone mass and low bone turnover rates. Therefore, an ideal implant should have a surface which is conducive to osseointegration regardless of the implant site, bone quality, and bone quantity. A large body of literature recommends the use of mini dental implants for stabilization of removable partial and complete dentures in selected situations.The 3M™ESPE™ mini dental implant (MDI) system makes use of a self-tapping threaded screw design and needs a minimal surgical intervention. Also, small-size implants have been widely used for orthodontic anchorage, single tooth replacements, fixing the surgical guides for definitive implant placement, and as transitional implants for the support of interim removable prosthesis during the healing phase of final fixtures. The MDIs have several advantages over the regular implants used for overdentures such as, simpler surgical protocol and minimally invasive surgery, and they can often be loaded immediately. This helps in reducing postoperative distress to the patient and minimizing resorption of the bone during healing. It has been shown that bone healing around immediately loaded transitional implants is not disturbed and causes no bone loss, which represents a solution for patients who have ridge deficiency and who cannot have surgery for medical reasons. Mini dental implants are also cost-effective, and the price of one MDI is 3.5 times lower than that of a standard size mandibular implant.

Despite the advantages of the MDI, evidence on their potential for osseointegration and long-term success is lacking. Newer implant systems entering the market must be studied first in vitro and then in vivo with animal models followed by human studies to demonstrate their osseointegration capability.

Modifications of implant surface properties have been shown to have a positive influence on the successful osseointegration of an implant. Surface properties such as roughness, topography, and chemistry are strongly related to the biocompatibility of implants. Thus, modulation of these properties can be useful means to improve implant osseointegration in patients with poor bone quality. The most common treatments used for implant surface modifications are acid etching and sandblasting. Implants with moderate surface coarseness demonstrate a better bone response than a smoother or rougher surface. When an implant is placed in the bone, a series of cell and matrix events takes place. These mainly include host response to the implant material and behavior of the implant in the host tissue, which culminates in an intimate deposition of a new bone on the implant surface.

The immediate event after implantation is adsorption of proteins which may facilitate cell attachment. Various studies show that direct osteoblast-implant interactions are critical for proper osseointegration. Cell culture models using osteoblastic cells are being commonly used to study bone-biomaterial interface.

In the current study, we examined the proliferation and differentiation characteristics of differentiated C2C12 cells and MC3T3-E1 preosteoblasts on surfaces mimicking the 3M™ESPE™ MDI (test group) and Ankylos® implants. The Ankylos® implant surface was used for comparison as it is a well-established and widely characterized standard implant.

The surfaces of 3M™ESPE™ MDIs are treated to impart roughness which includes sandblasting with aluminum oxide particles, followed by cleaning and passivation with an oxidizing acid. The Ankylos® implant has the FRIADENT plus surface (Dentsply Implants, Mannheim, Germany). It is formed by sandblasting in a temperature-controlled process and acid etching (hydrochloric, sulfuric, hydrofluoric, and oxalic acid) followed by a proprietary neutralizing technique. Considering that both surfaces were sandblasted and acid-treated, we hypothesize that there is no difference in the proliferation and differentiation capacity of osteoblastic cells when cultured on 3M™ESPE™ MDIs and standard implants.