International Journal of Oral Implantology, 02/2011

Purpose: The aim of this randomised controlled double-blinded clinical trial was to determine the efficacy of a new cross-linked membrane (VN) in guided bone regeneration (GBR) around exposed dental implants compared to a native collagen membrane (BG). Material and methods: A total of 16 patients in need of implant treatment at two different sites with osseous defects were planned for this split-mouth study. After inserting the dental implants, periimplant defects were treated according to the GBR technique using a VN membrane with prolonged resorption time in the randomised test site and a BG membrane in the control site. After a healing time of 6 months, mucoperiosteal flaps were elevated for the evaluation of the primary (vertical bone fill [ΔDL] and quality of newly formed tissue [QT]) and secondary outcome variables (infrabony defect height [DH], defect width [DW], defect depth [DD] and augmentation depth [AD]) and the sampling of biopsies apical to the implant shoulder. Results: A total of 16 patients fulfilled the initial non-surgical inclusion and exclusion criteria. However, the study was discontinued early after 9 surgically treated patients because unacceptable safety issues arose and severe infection related to the VN membranes. The VN membrane revealed statistically significantly more soft tissue dehiscence than the BG membrane (56% and 11%, respectively, P = 0.0455). In 3 of these 9 patients the VN membrane had to be removed due to infection early after the first follow-up visit. For the statistical analyses these sites were designated as the value of the baseline. The mean ΔDL values were 1.8 ± 1.6 mm at the VN site and 4.7 ± 3.3 mm at the BG site. The ΔDD values were 0.6 ± 1.0 mm and 1.1 ± 1.2 mm, respectively, and reached statistical significance (P = 0.0208, CI 95% = -2.9 [-5.2;-0.6]). The corresponding linear defect fill (DF) values were 44% and 78%, respectively. The clinical assessment of QT showed comparable median values at sites treated with VN (3, interquartile range: 0; 3.5) and BG (3, interquartile range: 3; 4) without statistical significance. The histomorphometric analysis showed an average area density of 24.4% (SD 10.3, range 8-35%) newly formed bone at the test sites and of 35.0% (SD 20.6, range 8-60%) at the control sites. The histological data showed only some trends and did not reach statistical significance. Conclusion: In the present study, the VN membranes with prolonged resorption time demonstrated significantly more adverse events and insufficient bone regeneration compared to the native BG membranes and no advantages in favour of the VN membranes were detectable. Keywords: clinical research, collagen membrane, cross-linking, guided bone regeneration

Purpose: To compare the subgingival microbiota around two differently designed implant systems that were in function for more than 12 years in a randomised split-mouth study design, and to compare the outcome with natural dentition. Materials and methods: A total of 18 partially edentulous patients received at least two TiOblast™ (Astra Tech) and two Brånemark (Nobel Biocare) implants following a split-mouth design. At the last follow-up visit, periodontal parameters (probing depth, bleeding on probing and plaque) were recorded and intraoral radiographs were taken to calculate bone loss. Subgingival plaque samples were collected for culture, qPCR and checkerboard DNA-DNA hybridisation analysis. These data were related to implant design and bone loss. This study setup allowed a comparison of 34 Astra Tech (Impl A) with 32 Brånemark (Impl B) implants. Results: During the 12-year follow up, five patients dropped out. One Brånemark implant was lost before abutment connection in a dropout patient. Mean bone loss between loading and year 12 was 0.7 mm (range: -0.8-5.8) (Impl A), and 0.4 mm (range: -1.1-4.1) (Impl B). No significant microbiological differences (qualitative and quantitative) could be observed between both implant types. Compared to teeth, subgingival plaque samples from implants did not reach the concentration of pathogens, even after 12 years of function. Conclusions: These data show that both implant systems (with differences in macro-design and surface characteristics), in patients with good oral hygiene and a stable periodontal condition, can maintain a successful treatment outcome without significant subgingival microbiological differences after 12 years of loading. The presence of periodontopathogens did not necessarily result in bone loss. Keywords: implant systems, microbiology, peri-implant, split-mouth design, subgingival

Purpose: To evaluate whether a human dermis graft (HDG) could be used instead of an autogenous connective tissue graft (ACT) to increase gingival thickness and to cover multiple gingival recessions. Materials and methods: Forty-two consecutive patients with multiple gingival recessions were offered the option to have their recessions covered either with ACTs harvested from their palate or with HDGs. Outcome measures were complications, gingival recession changes (REC), gingival biotype changes (BIO), probing attachment level changes (PAL), probing pocket depth changes (PPD) and keratinised mucosa height changes (KER) evaluated by an independent and masked assessor after 6 months. Results: Twenty-one patients with 110 recessions opted for ACTs and 21 patients with 160 recessions opted for HDGs. No patients dropped out. Only one minor complication occurred at one HDG-treated site. Recessions significantly decreased in both groups (2.7 mm for ACT and 2.0 mm for HDG), however, ACTs resulted in a statistically significantly improved root coverage and CAL of 0.5 mm, as well as 18% more root coverage than HDGs. Conclusions: HDGs can be an effective alternative to ACTs for covering exposed roots and increasing soft tissue thickness, especially when many recessions have to be treated in the same mouth, though they may provide slightly less root coverage than ACTs. Keywords: aesthetic, connective tissue graft, gingival recession, preference controlled clinical trial, soft tissue augmentation

Purpose: Several classification systems have been proposed in the literature, but none of them has been validated by means of an appropriate statistical analysis and, therefore, it is unknown whether these systems work in the same manner among different clinicians. The aim of the present study is to investigate the intra- and inter-rater agreement of a new system to classify gingival recession defects and to evaluate its agreement among different clinicians. Materials and methods: A new classification system was proposed and tested considering the following three factors: the amount of keratinised tissue (=2 mm), the presence/absence of noncarious cervical lesions and the presence/absence of interproximal attachment loss. Kappa-statistics were performed to analyse the intra-rater and inter-rater agreement among three blinded examiners. Results: A total of 120 gingival recessions were evaluated using the new classification system. The intra-rater agreement ranged from 0.74 to 0.96 for the variable keratinised tissue, from 0.67 to 0.94 for the variable non-carious cervical lesions and from 0.70 to 0.92 for the variable interproximal attachment loss. The inter-rater agreement values ranged from 0.70 to 0.85 for keratinised tissue, from 0.54 to 0.59 for non-carious cervical lesions and from 0.54 to 0.77 for the interproximal attachment loss. Conclusions: Based on the results of this study, the proposed new classification system showed moderate to substantial agreement among investigators when used in the present study population and was therefore able to diagnose the severity of gingival recession defects. Keywords: classification, diagnosis, gingival recession

Purpose: The aim of this survey is to assess the different radiographic interpretations of simulated dental implant cases among a group of specialists in oral surgery. Material and methods: A total of 76 active members of the Italian Society of Oral Surgery and Implantology were recruited for the study. The participants in the study were requested to assign scores to radiographic images of 12 simulated cases of dental implants: a baseline and follow-up image for cases with different bone loss (0, 1 or 5 mm), implant length (8 or 12 mm) and years of follow-up (1 or 5 years). Results: In total, 63 active members agreed to participate in the survey. The inter-rater agreement was 0.86 (CI 95% 0.74; 0.95). In cases where the bone loss was absent (0 mm) no difference was detected at 1 or 5 years of follow-up. In contrast, when bone loss was present (1 or 5 mm) the longer follow-up (5 years) revealed the highest score. The lowest score was attributed to 5 mm of bone loss and 1 year of follow-up. Moreover, a significant difference between the short (8 mm) and the long (12 mm) implant was observed (score difference 0.45; CI 95% 0.28; 0.63). Conclusions: This investigation suggests that subjective evaluation of radiographs on simulated implants by skilled clinicians is rather uniform, and bone loss, follow-up and implant length are factors considered in the perception of implant success. Keywords: dental implants, outcome assessment, radiography, success

Purpose: This case series aimed to evaluate the clinical outcome of a crestal approach technique in sinus floor elevation surgery with insertion of an alloplastic material. Material and methods: A total of 50 edentulous patients received 64 implants and sinus floor elevation in posterior maxillae with residual crestal height 1.2 to 9.8 mm, and larger than 7 mm in width. Drilling perforation was performed until the sinus floor was felt. The sinus mucosa was then lifted. Hydroxyapatite granules were placed and implants were immediately inserted. Three months later, definitive crowns were cemented and patients were followed up for 18 months. Outcome measures were implant failures, complications and radiographic bone height gain measured 18 months after prosthetic loading. Results: No patient dropped out and all implants were successfully osseointegrated. Only minimal postoperative patient discomfort was reported. Only one complication occurred: a minor perforation of the sinus membrane with no negative consequences. At the time of implant insertion, the residual bone height mean value was 6.20 mm (±2.22). After surgery and at the last follow-up, the mean height of bone was 15.26 (±3.19) and 15.40 mm (±4.21), respectively. Conclusion: The procedure was able to obtain sinus elevation and implant osseointegration. Keywords: dental implant, sinus floor elevation