Osseointegration at Implants Installed in Composite Bone: A Randomized Clinical Trial on Sinus Floor Elevation.

Osseointegration of implants installed in conjunction with sinus floor elevation might be affected by the presence of residual graft. The implant surface characteristics and the protection of the access window using a collagen membrane might influence the osseointegration. To evaluate these factors, sinus floor elevation was performed in patients using a natural bovine bone grafting material. The access windows were either covered with a collagen membrane made of porcine corium (Mb group) or left uncovered (No-Mb group) and, after six months, two mini-implants with either a moderate rough or turned surfaces were installed. After 3 months, biopsies containing the mini-implants were retrieved, processed histologically, and analyzed. Twenty patients, ten in each group, were included in the study. The two mini-implants were retrieved from fourteen patients, six belonging to the Mb group, and eight to the No-Mb group. No statistically significant differences were found in osseointegration between groups. However, statistically significant differences were found between the two surfaces. It was concluded that implants with a moderately rough surface installed in a composite bone presented much higher osseointegration compared to those with a turned surface. The present study failed to show an effect of the use of a collagen membrane on the access window.

Healing at implants installed in osteotomies prepared either with a piezoelectric device or drills: an experimental study in dogs.

OBJECTIVE: To compare osseointegration and marginal bone level at implants placed in osteotomies prepared with either conventional drills or a piezoelectric device. MATERIAL AND METHODS: Three months after the extraction of all mandibular premolars and first molars, two recipient sites were selected. The osteotomies were randomly prepared with either conventional drills (drill sites) or a piezoelectric device (piezoelectric sites). Implants were installed and a submerged healing was allowed. The animals were euthanized in groups of six after 4 and 8 weeks of healing. Biopsies were obtained for histological preparation. Coronal level of osseointegration (bone level) and bone-to-implant contact percentage (BIC%) were evaluated. RESULTS: After 4 weeks of healing, the bone level was 0.6 ± 0.9 mm for the piezoelectric sites and 1.6 ± 0.7 mm for the drill sites (p = 0.173). After 8 weeks, the respective measures were 0.9 ± 0.3 mm and 1.0 ± 1.1 mm (p = 0.917). After 4 weeks of healing, a new bone apposed onto the implant surface was found at fractions of 54.9 ± 6.7% and 55.1 ± 16.6% for the piezoelectric and the drill sites, respectively (p = 0.674). The respective total bone fractions, including new and old bone, was 64.0 ± 4.8% and 63.4 ± 20.4% (p = 0.917). After 8 weeks, a new bone increased to 67.4 ± 6.7% and 62.9 ± 12.5% for the piezoelectric and the drill sites, respectively (p = 0.463). The respective total bone fractions were 70.4 ± 5.5% and 67.8 ± 12.1% (p = 0.753). CONCLUSIONS: The use of a piezoelectric device for implant site preparation is a safe procedure that allows a proper integration since the early periods of healing similar to that observed using conventional drills.

Healing at implants installed from ~ 70- to < 10-Ncm insertion torques: an experimental study in dogs.

OBJECTIVE: To evaluate histologically the early healing at implants installed with different insertion torques MATERIAL AND METHODS: Three months after the extraction of the mandibular premolars and of the first molars, two implants were installed monolaterally in the premolar and two in the molar regions of the edentulous alveolar ridge of twelve dogs. The recipient sites were prepared using drills of different diameter to obtain insertion torque of different values, i.e., 30 Ncm (control) or ~ 70 Ncm (test) in the premolar region, and < 10 Ncm (test) or ~ 50 Ncm (control) in the molar region. Six animals were euthanized after 4 weeks and six after 8 weeks of healing. Histological analyses were performed, and the Wilcoxon test was applied for statistical analyses. RESULTS: After 4 weeks of healing, in the premolar region, the new bone in contact with the implant surface was 65.0 ± 4.6% and 53.9 ± 13.5% at the ~ 30-Ncm and ~ 70-Ncm sites, respectively (p = 0.075). In the premolar region, new bone proportions were 51.4 ± 17.0% and 67.3 ± 7.0% at the < 10-Ncm and ~ 50-Ncm sites, respectively (p = 0.046). After 8 weeks of healing, in the premolar region, new bone reached fractions of 77.7 ± 16.2% at the ~ 30-Ncm sites, and 68.3 ± 12.1% at the ~ 70-Ncm sites (p = 0.028). In the molar region, new bone presented proportions of 70.2 ± 6.4% at the < 10-Ncm sites and 76.2 ± 9.4% at the ~ 50-Ncm sites (p = 0.173). CONCLUSIONS: The insertion torque influenced the osseointegration of implants. Higher values of bone-to-implant contact percentages were registered for insertion torques of ~ 30 Ncm and ~ 50 Ncm. Implants inserted with torque < 10 Ncm became integrated with an optimal osseointegration.

Effect of lack of plaque control after the surgical treatment of peri-implantitis at surfaces with different characteristics: an experimental study in dogs.

OBJECTIVE: The aim of the present study was to evaluate the effect of the induction of peri-implantitis and of plaque accumulation on implants with different surface characteristics after the surgical treatment. MATERIAL AND METHODS: All mandibular premolars and first molars were extracted bilaterally in six dogs. After 3 months, two non-submerged implants were installed, each with either a hydrophilic sandblasted and acid-etched surface stored in saline solution (SLActive) or an acid-etched and modified with calcium ions surface (UnicCa). After 3 months, ligatures were placed in the sulcus around the implants to induce an experimental peri-implantitis and plaque accumulation was allowed. After 3 months, ligatures were removed and, after one more month of plaque accumulation, a surgical treatment was performed using gauzes soaked in saline and irrigations. X-rays were taken at this stage. Plaque control maintenance was established at the control sites, while plaque accumulation was allowed at the test sites (plaque sites). After 5 months, biopsies were obtained. Marginal bone levels were compared between x-rays and histological assessments. RESULTS: At the time of peri-implantitis treatment, two SLActive implants were lost. At the euthanasia, seven more implants were lost only in the plaque group, one control and six test implants. The calculated mean values of the marginal bone level of the two surfaces at the treatment were 3.65 ± 1.71 mm in the control group, and 3.65 ± 1.76 mm in the plaque group (p = 0.463). The additional marginal bone loss after 5 months from surgical treatment was 0.67 ± 0.67 mm (UnicCa, 0.48 ± 1.06 mm and SLActive, 0.79 ± 2.10 mm) and 3.11 ± 1.38 mm (UnicCa, 2.67 ± 1.87 mm and SLActive, 3.94 ± 2.11 mm) for the control and plaque groups, respectively (p = 0.028). CONCLUSIONS: The lack of plaque control after the surgical treatment of the peri-implantitis strongly influenced the marginal bone loss.