Methods to Improve Osseointegration of Dental Implants in Low Quality (Type-IV) Bone: An Overview

Abstract

Nowadays, dental implants have become more common treatment for replacing missing teeth and aim to improve chewing efficiency, physical health, and esthetics. The favorable clinical performance of dental implants has been attributed to their firm osseointegration, as introduced by Brånemark in 1965. Although the survival rate of dental implants over a 10-year observation has been reported to be higher than 90% in totally edentulous jaws, the clinical outcome of implant treatment is challenged in compromised (bone) conditions, as are frequently present in elderly people. The biomechanical characteristics of bone in aged patients do not offer proper stability to implants, being similar to type-IV bone (Lekholm & Zarb classification), in which a decreased clinical fixation of implants has been clearly demonstrated. However, the search for improved osseointegration has continued forward for the new evolution of modern dental implants. This represents a continuum of developments spanning more than 20 years of research on implant related-factors including surgical techniques, implant design, and surface properties. The methods to enhance osseointegration of dental implants in low quality (type-IV) bone are described in a general manner in this review.

Keywords: bone regeneration; dental implants; osseointegration; surface modifications.

Figure 1

Lekholm & Zarb classification: Type I, the entire bone is composed of very thick cortical bone; Type II, thick layer of cortical bone surrounds a core of dense trabecular bone; Type III, thin layer of cortical bone surrounds a core of trabecular bone of good strength; and Type IV, very thin layer of cortical bone with low density trabecular bone of poor strength.

Figure 2

Dental implants are mostly available as (A) threaded cylindrical-shaped or (B) conical (root)-shaped (Images are courtesy of Baltic Osseointegration Academy/Public Information. http://www.boaoffice.lt/EN/9/). Radiographic images displaying clinical cases in which both ((C,D), respectively) implant-designs are inserted in the jaw bone.

Figure 3

Illustration representing biological beneficial of surface coatings on dental implants. Drugs or bioactive factors can be delivered to the local bone microenvironment around implants, in which osteogenic factors and process are promoted; thereby increasing osteoblast differentiation and mineralization.