Does thread design influence relative bone-to-implant contact rate of palatal implants?

Abstract

To determine histologically whether (a)changing the thread design between first- and second-generation palatal implants (Straumann, Basel, Switzerland) influences the bone-to-implant contact (BIC) rate of palatal implants subjected to conventional loading, and (b)whether histological evidence of peri-implantitis appears in this setting. Patients who had received an orthodontic palatal implant for skeletal anchorage between January 1998 and December 2007 were examined. First-generation palatal implants (Straumann, Basel, Switzerland) 3.3mm in diameter and 6mm or 4mm long were used, as were second-generation implants 4.1mm in diameter and 4.2mm long. After completion of active orthodontic treatment, the implants were removed and prepared for histological investigation. This study was designed as a comparative analysis of a series of two cases: 28explanted first-generation (n=14) and second-generation (n=14) palatal implants were analyzed. Bone healing was achieved with all implants. Both types of implants revealed a mean bone-to-implant contact (BIC) rate that was nearly equal: 80.7% (SD 10.7%) for the first-generation and 81% (SD 13.1%) for the second-generation implants. Bone resorption was only observed in 5palatal implants (3/14 of the first, and 2/14 of the second generation). Despite differing thread designs, second-generation palatal implants revealed similar bone-to-implant contact rates as did those of the first generation. Few patients presented bone resorption in the peri-implant bone.