Patterns of tissue remodeling after placement of ITI dental implants using an osteotome technique: a longitudinal radiographic case cohort study

The aim of this prospective study was to document radiographically tissue remodeling patterns around ITI implants placed according to an osteotome technique. In 19 consecutive patients from a private practice, 25 implants of the ITI Dental Implant System were placed subjacent to the sinus floor. Implant beds were pre-prepared with pilot drills and/or using the Summers Osteotome Kit. Bio Oss particles were mixed with autologous bone and inserted into the apex area. Implants were placed self-tapping. The sinus floors were thereby pushed up with attempts not to sever the Schneiderian membrane. Healing occurred submerged or semi-submerged and was uneventful in 24/25 implants. At 1 year, all implants had been restored with crowns or short fixed partial dentures. One implant was lost in the first 3 weeks, but was replaced 6 months later in a second attempt. Intraoral radiographs were obtained presurgically and postsurgically at 3 and 12 months. The mean preoperative distance between the sinus floor and the crest was 7.0 mm (range 2.3-10.3 mm). The mean distances between the implant apex and the initial sinus floor were: 3.66 +/- 1.74 mm mesially and 4.44 +/- 1.62 mm distally. The mean height of the new bone reaching apically and mesially to the implants was 1.52 +/- 2.48 mm at surgery, but was reduced significantly to 1.24 +/- 1.30 mm at 3 months and 0.29 +/- 1.91 mm after 12 months (Hotelling's test P< or =0.01). Similar values were obtained at the disto-apical aspects. In an attempt to assess periapical bone/graft remodeling, a novel index was applied: 0=no bone/graft visible, 1=cloudy appearance of new bone/graft, 2=clearly visible new bone/graft disappearing structures of original sinus floor, 3=new bone/graft with new cortical plate and the former boundary of the sinus floor disappearing. This index increased statistically significantly from baseline to 12 months (Hotelling's test P< or =0.02). In conclusion, this study shows that in areas with reduced bone height subjacent to the sinus, an osteotome technique may provide a minimally invasive way to obtain implant abutments predictably. The grafted area apical to the implants undergoes shrinkage and remodeling. The original boundary of the sinus is eventually consolidated and replaced by a new cortical plate. In addition to the linear measurements, the novel index may assist in assessing periapical remodeling at implants placed with an osteotome technique.