Mauro Donati

Immediate functional loading of implants in single tooth replacement: a prospective clinical multicenter study

OBJECTIVES The aim of the present study was to evaluate the outcome of immediate functional loading of implants in single-tooth replacement using two different installation procedures. MATERIAL AND METHODS One hundred and fifty-one subjects, who required single-tooth rehabilitation in the area of 15-25 and 35-45, were enrolled in eight private clinics in Italy. The implant sites were randomly allocated to one of the following treatment groups. In the control group, in which a standard preparation procedure for implant placement and submerged healing of the implant was used, abutment connection and loading of the implants were performed 3 months after installation. In the test group 1, a standard preparation procedure for the implant placement and immediate functional loading of implant was carried out. In the test 2 group, however, a modified implant installation procedure (osteotome technique) was used followed by immediate functional loading of the implant. Clinical and radiographic examinations were performed at 3 and 12 months of follow-up at all sites. RESULTS Three implants (5.5%) from the test 2 group (osteotome preparation) and one (2%) from the test 1 group (conventional drill preparation) failed to integrate and were removed one and three months after implant installation. The mean marginal bone loss assessed at 12 months was 0.31 mm (test 1), 0.25 mm (test 2) and 0.38 mm (control) (no statistically significant differences were found between the three treatment groups.) CONCLUSION It is suggested that immediate functional loading of implants that are placed with a conventional installation technique and with sufficient primary stability may be considered as a valid treatment alternative in a single-tooth replacement.

B-1a cells and plasma cells in periodontitis lesions

BACKGROUND AND OBJECTIVE Host response mechanisms in periodontal tissues are complex and involve numerous systems of interactions between cells. The B-cell lineage seems to predominate in chronic periodontitis lesions. The aim of the present investigation was to study the correlation between inflammatory cells and some functional markers in gingival lesions obtained from subjects with severe chronic periodontitis. MATERIAL AND METHODS Thirty-eight Caucasian subjects volunteered to take part in the study. A gingival biopsy from one randomly selected diseased proximal site (probing pocket depth > 6 mm and bleeding on probing positive) was obtained from each patient. Immunohistochemical preparation was used to identify inflammatory cells and functional markers. Correlations between the different percentages of cell markers were analyzed by pairwise correlation. RESULTS B cells (B-1a and B-2 cells) occurred in larger proportions than T cells and plasma cells. A statistically significant correlation was found between the percentage of B-1a cells and plasma cells and between all B lymphocytes and plasma cells. About 60% of B lymphocytes exhibited autoreactive features. CONCLUSION It is suggested that B-1a cells constitute a significant part of the host response in periodontitis lesions and that plasma cells may develop from both B-2 and B-1a cells.

The Sp1 transcription factor binds to the G-allele of the –1087 IL-10 gene polymorphism and enhances transcriptional activation

The objectives of this study were to evaluate the influence of the −1087 single nucleotide polymorphism (SNP) on the gene expression of interleukin (IL)-10 and to identify transcription factors binding to this site in B cells. Using electrophoretic mobility-shift assays and nuclear extract from the DG75 B-cell line, we demonstrated that the Sp1 transcription factor bound to the −1087 G-allele of the IL-10 promoter and that the transcription factors PU.1 and Spi-B bound to both the G- and A-alleles. Transient transfections showed that lipopolysaccharide stimulation resulted in a 15-fold increase in promoter activity for the G-allele as compared to a 6-fold increase for the A-allele. Co-transfection with Sp1 expression vector in Sp1-deficient SL2 cells leading to Sp1 binding to the G-allele of the −1087 SNP resulted in increased IL-10 promoter activity. The results suggest a role for Sp1 transcription factor in the activation of IL-10 through the G-allele of the −1087 SNP in response to inflammatory signals.

Marginal Bone Preservation in Single-Tooth Replacement: A 5-Year Prospective Clinical Multicenter Study

BACKGROUND Few long-term studies are available comparing immediate and conventional loading protocols of implant-supported single-tooth replacement. PURPOSE The aim of the present randomized controlled clinical trial was to evaluate prospectively the 5-year clinical and radiological outcome of immediate functional loading implants used in single-tooth replacement. MATERIALS AND METHODS One hundred fifty-one subjects, who required single-tooth rehabilitation in the area from position 15 to 25 and from 35 to 45, were enrolled in eight private clinics in Italy. A randomization protocol was applied to allocate the implants in three treatment groups: one control group and two test groups. In the control group, implant placement was performed according to a conventional drilling procedure, and the implants were submerged for 3 months before abutment connection and loading. Implants allocated in the test group 1 and 2 followed an immediate functional loading protocol. While in test group 1, implant placement was performed according to conventional drilling procedure, in test group 2, a modified implant installation procedure (osteotome technique) was applied. Clinical and radiographic examinations were performed during the 5-year follow-up, and technical and biological complications were registered. RESULTS Although four implants (three in the test group 2 and one in the test group 1) were lost in the immediate functional loading groups in the first year of follow-up, no further implant loss occurred in any of the treatment groups in the following monitoring period up to 5 years. No significant differences on marginal bone level changes were observed between the treatment groups. About 52% of all implants showed bone gain in the period from 1-year to 5-year follow-up. The percentage of all implants that in the same interval of time showed bone loss was about 28%. Although few technical complications were recorded in the period of time up to 5 years, implants showing biological complication were 5.7%. CONCLUSION It is suggested that implants installed with a conventional installation technique together with an immediate functional loading protocol may be considered as a valid treatment alternative in a long-term perspective when used in a single-tooth replacement in an esthetic area.

B-1a Cells in Experimental Gingivitis in Humans

BACKGROUND Although previous studies revealed the presence of autoreactive B cells (B-1a cells) in periodontitis lesions, no evidence was provided for an active role of such cells in the host response to microbial challenge. The aim of the present investigation was to study the reaction of B-1a cells to de novo plaque formation in subjects who were treated for severe chronic periodontitis. METHODS Fifteen white subjects with generalized, severe chronic periodontitis volunteered. Surgical periodontal therapy was performed in all quadrants of each subject after a period of infection control. After 6 months of healing (baseline), two gingival biopsies were harvested from each patient (probing depth <4 mm and no bleeding on probing; healed sites). The experimental gingivitis model was applied, and plaque accumulation was allowed for 3 weeks. Two additional biopsies were collected and prepared for immunohistochemical analysis on day 21. RESULTS The biopsies retrieved after 3 weeks of plaque accumulation contained larger proportions of CD19+ and CD5+ cells (B-1a cells) than biopsies representing baseline (healed sites) (7.38% +/- 2.80% versus 5.96% +/- 2.48%). The tissue fraction of cells carrying the markers for CD3 (T cells), CD19 (B cells), and Bcl2 (apoptosis-associated marker) were significantly larger in tissue samples collected after 3 weeks of plaque accumulation than in specimens from baseline (healed sites). CONCLUSION Autoreactive B cells (B-1a cells) are involved in the host response to microbial challenge in subjects with chronic periodontitis.