INTRUSION ANCHORAGE POTENTIAL OF TEETH VERSUS RIGID ENDOSSEOUS IMPLANTS - A CLINICAL AND RADIOGRAPHIC EVALUATION

The purpose of this study was to compare the intrusion anchorage poten tial of teeth to osseointegrated titanium implants. Titanium implants were surgically placed unilaterally in a healed mandibular fourth prem olar extraction site in eight adult mongrel dogs. The implants were su rgically uncovered 3 months later and second stage abutments with sold ered edgewise brackets secured. Edgewise brackets were also placed on the ipsilateral third premolars and on the contralateral third and fou rth premolars. Segmental edgewise arch wires were placed between the i mplant and the third premolar and between the contralateral third and fourth premolars. Intrusion arch wire bends (v-bends) just mesial to t he implant and the fourth premolar brackets were adjusted to apply a 5 0 to 60 gm intrusive force to the third premolars, bilaterally. Seven weeks later this force was increased to approximately 100 gm. Force le vels were monitored biweekly for a total period of 16 weeks. Superimpo sition of initial and final periapical radiographs with bone markers d emonstrated that for each dog the implant remained immobile and the th ird premolar on the implant anchor side was intruded in a curved path. On the contralateral side of the arch the dental anchor (fourth premo lar) underwent an adverse reactive tip-back movement, and the third pr emolar was not intruded. We conclude that rigid endosseous implants ar e superior to dental anchorage for orthodontic intrusion of teeth and offer a potential means to intrude anterior teeth in adult patients wi th missing posterior teeth.