A prospective randomized split-mouth study comparing iliac onlay grafts in atrophied edentulous patients: covered with periosteum or a bioresorbable membrane.

PURPOSE: In this prospective study, solid monocortical iliac onlay grafts of the maxilla were randomly covered with a bioresorbable membrane and periosteum within the maxilla. Histologic specimens were analyzed by light microscopy after a healing period of three months and the rate of resorption of the grafts were measured. MATERIALS AND METHODS: Fourteen patients (9 females and 5 males), with a mean age of 56 years (range 25-72) underwent augmentation with avascular iliac onlay bone grafts. The grafts were randomly covered either with a bioresorbable membrane (MC) or periosteum (PC). Resorption was measured with a digital caliper at the microscrews (slashed circle 1.5 mm) used to fixate the graft. Histologic evaluation of the specimens derived from the graft with a trephine bur (slashed circle 2 mm) from the implant site at implant placement after a 3-month healing period. Statistical evaluation of the data was performed using Analysis of variance and the Wilcoxon signed rank test. RESULTS: Clinical appearance of the augmented bone after 3 months showed a dense cortical layer with good vascular perfusion. Thirty-three sites in 13 patients (one dropped put) were analyzed histomorphometrically and showed an average of 46% newly formed bone with no significant difference between the groups (P=0.46). The mean resorption rate at 56 measured sites was 1.2 mm (range 0.3-3.4 mm) after 3 months, with no significant difference between the MC sites and the PC sites (P=0.38). DISCUSSION: Histomorphometry of new bone formation after 3 months demonstrates no significant difference between the PC and MC groups. Initialization of graft resorption can be seen after 3 months with no significant difference as to whether the graft was covered with a membrane or the periosteum. CONCLUSION: This study provides evidence that after avascular iliac bone grafting, the revascularization of the graft was sufficient after 3 months regardless of the graft coverage with no effect on the amount of initial resorption of the graft.

Association of Treponema spp. with canine periodontitis.

To evaluate the association of oral Treponema (T.) spp. with severity of canine periodontitis, subgingival plaque samples of dogs of various breeds undergoing surgery were investigated. A wide range of oral Treponema spp. was analysed by a molecular and culture-independent approach applying DNA-DNA dot blot hybridization analysis and fluorescence in situ hybridization using Treponema specific oligonucleotide probes specific for phylogenetic groups I-VII of oral treponemes as well as probes specific for T. socranskii and T. denticola. To assess the periodontal status of affected dogs clinical parameters were measured and the periodontal status was classified from grade 0 (physiological periodont) to 3 (severe periodontitis). The periodontal status correlated significantly with an increasing concentration of volatile sulfur compounds (VSC, r=0.854) determined with a Halimeter, indicating a positive correlation between the presence of VSC-producing bacteria and periodontitis. In this study Treponema spp. of phylogenetic groups III, V-VII were not detected in any sample, whereas T. denticola-like treponemes were found only in 2 of 51 animals. However, treponemes belonging to phylogenetic groups I, II and IV of oral treponemes or T. socranskii were found in up to 64.84% of the dogs. The detection rate of Treponema spp. was significantly associated with an increased periodontal status. Treponemes present in periodontal lesions were also visualized by fluorescence in situ hybridization of gingival biopsies showing Treponema spp. not only in the microbial biofilm but also within the gingival tissue. The data presented here indicate that oral Treponema spp. are associated with canine periodontitis. Similar to human periodontitis, treponemes of groups I, II and IV and T. socranskii were found more frequently the higher the degree of periodontitis was.