78 Theories and techniques of oral implantology

of the site, and loose epithelial tissue tends to invaginate toward the base of the implant, where it provides neither a tight bond nor any stimulation on bone.

Mechanical stimulation

As the periodontal tissues of a normal tooth are affected by mechanical stimulation, so are those around an implant. Vertical, lateral, and rotary movements must be confined within certain physiologically compatible limits. This is accomplished by both the design of the implant and the proper, care-fully balanced occlusion of the prosthesis set over it.

Whether or not an implant must be stabilized immediately after its insertion to prevent traumatic movement depends upon its design. Post type implants with protruding abutment posts must be protected against lateral movements exerted by the tongue, cheeks, and lips. Each time a person speaks, his tongue and lips move against the teeth and press on them. Swallowing creates a vacuum that pulls the cheeks inward. Chewing can also disturb an implant abutment post if the bolus is chewed in the area, but normally vertical movements do not disturb an implant abutment post. Without its crown, the abutment post is out of occlusion.

Lateral movements tend to create a leverage action on an unstabilized post type implant post. They can also pivot the implant along its vertical axis (Fig. 3-38). None of these movements is beneficial to healing.

When an internally-threaded implant is used, little of the uppermost post protrudes into the oral

Fig. 3-38. A post type implant must be protected against lateral movements because they may dislodge it by spinning it on its axis.

cavity above the crest of the ridge. This certainly reduces the danger of lateral movements by removing the focus of action. It is still advisable, however, to splint the implant. Splinting an implant not only protects it but also places it in functional occlusion.

Functional occlusion stimulates the organization of compact, regularly formed fiber bundles within the healing connective tissues and of functional stress patterns within bone, as well as the apposition of new bone. In a healed site the continued stimulation from good occlusal tension keeps the tissues normal and healthy—an essential in an implant's long-term success.

Unlike a post implant, a blade need not be immediately stabilized. Because of its unique design, it is stable from the moment of insertion. Lateral movements against the post cannot pivot the blade or spin it on its axis, because these forces are counter-acted by the broad surface contact between blade and bone (Fig. 3-39). Naturally the abutment post of the blade also lies below the occlusal plane, and there is little danger of undue vertical pressure.

The method of inserting the blade implant re-quires reflecting the soft tissues overlying the bone. Leaving the implant unsplinted encourages more rapid healing of these tissues. The few days' lapse between inserting the implant and placing it in functional occlusion is not enough to retard the healing of the tissues of the implant site.

Fig. 3-39. The blade implant is not normally adversely affected by lateral movements because its large surface con-tact with bone provides adequate stabilization.