Análise das estabilidades primária e secundária de implantes curtos unitários instalados na região posterior

Abstract

Clinical evidences suggest that the stability of dental implants plays an important role on the success of osseointegration. However, there is not sufficient information with respect to the stability of short (6-mm long) implants. Thus, the aims of this study were: 1) to assess clinically and longitudinally the stability of short implants in relation to the bone quality, by means of insertion torque, resonance frequency analysis (RFA) (Osstell®) and damping capacity (PTV) (Periotest®); and 2) to evaluate the correlation among these three techniques. Thirty-nine one-stage implants (Straumann®, SLActive, ø4.1 x 6-mm long) were placed in the posterior region of the maxilla and the mandible in 18 patients with ages ranging between 25 and 76 years old. The bone quality was identified by the surgeon s tactile sensitivity at the moment of the perforation and classified according to the Lekholm & Zarb classification (1985) (types I-IV). The insertion torque was measured using the manual wrench (Straumann®) and divided into three groups: <15 N.cm, between 15 and 35 N.cm and, finally, >35 N.cm. The PTV values were measured immediately after the manual torque, at the implant assembler level. For the RFA values, a mean was calculated for the mesio-distal and bucco-lingual measurements. The RFA and PTVs assessments were repeated at the moment of the crown installation (3 months later). The results showed a significant effect of bone quality on the stability values of the implant. Insertion torque values were significantly higher for bone types I-II than for bone types III and IV. Statistical difference was found only for PTV values between bone types I and II compared to bone type IV. For the RFA values, implants placed in types I-II and III presented ISQ significantly higher than implants placed in type IV bone. Besides that, regardless of the type of bone, the mean ISQ values were significantly higher after the osseointegration period (mean=79.36) than that at the moment of the placement of the implant (mean=68.29). The results of this study showed that bone quality influences on the values of primary and secondary stability, presenting moderate correlation among the three methods of stability assessment.