Stefano Storelli

A Double‐Blind Randomized Controlled Trial (RCT) of Titanium‐13Zirconium versus Titanium Grade IV Small‐Diameter Bone Level Implants in Edentulous Mandibles – Results from a 1‐Year Observation Period

BACKGROUND The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two-implant overdenture has been recommended as the standard of care. The use of small-diameter implants may extend treatment options and reduce the necessity for bone augmentation. However, the mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable. PURPOSE This randomized, controlled, double-blind, multicenter study investigated in a split-mouth model whether small-diameter implants made from Titanium-13Zirconium alloy (TiZr, Roxolid™) perform at least as well as Titanium Grade IV implants. METHODS AND MATERIALS Patients with an edentulous mandible received one TiZr and one Ti Grade IV small-diameter bone level implant (3.3 mm, SLActive®) in the interforaminal region. The site distribution was randomized and double-blinded. Outcome measures included change in radiological peri-implant bone level from surgery to 12 months post-insertion (primary), implant survival, success, soft tissue conditions, and safety (secondary). RESULTS Of 91 treated patients, 87 were available for the 12-month follow-up. Peri-implant bone level change (-0.3 ± 0.5 mm vs -0.3 ± 0.6 mm), plaque, and sulcus bleeding indices were not significantly different between TiZr and Ti Grade IV implants. Implant survival rates were 98.9 percent and 97.8 percent, success rates were 96.6 percent and 94.4 percent, respectively. Nineteen minor and no serious adverse events were related to the study devices. CONCLUSION This study confirms that TiZr small-diameter bone level implants provide at least the same outcomes after 12 months as Ti Grade IV bone level implants. The improved mechanical properties of TiZr implants may extend implant therapy to more challenging clinical situations.

Systematic review of the survival rate and the biological, technical, and aesthetic complications of fixed dental prostheses with cantilevers on implants reported in longitudinal studies with a mean of 5 years follow-up.

OBJECTIVE A systematic review was carried out to evaluate the success and survival rate of implants supporting cantilever prosthesis, as well as the incidence of technical and biological complications. MATERIAL AND METHODS A MEDLINE search was conducted up to December 2011 for studies with a mean follow-up of 5 years or more. Two independent reviewers screened the retrieved articles and extracted the data independently. Data on survival, failure, mechanical/technical and biological complications were analyzed. RESULTS One-hundred and sixty articles were selected as abstract. Only 18 underwent a full-text analysis and only six were included in the study. The estimated cumulative survival rate of implants supporting cantilevered prosthesis was 98.9% (95% CI: 97.4-99.5%), whereas ICFDP survival was estimated to be about 97.1% (95% CI: 90.1-99.2%). Implant failures before prosthetic delivery were not considered. Biological complications were estimated to be 5.7% (95% CI: 4.2-7.6%) at implant level after 5 years. Technical complications were analyzed: the most common complications were veneer fractures (5-year estimate: 10.1%; 95% CI: 3.7-16.5%) and abutment screw fractures (5-year estimate: 1.6%; 95% CI: 0.8-3.5%). Decementation and screw loosening were estimated to be at 5 years 5.9% (95% CI: 1.7-16.8%) and 7.9% (95% CI: 3.2-18.2%), respectively. Implant fracture was rare (5-year estimate: 0.7%; 95% CI: 0.1-4.7%); no framework fracture was reported. Radiographic bone level changes did not yield statistically significant differences. No aesthetic outcome was reported. CONCLUSIONS ICFDPS can be considered a reliable treatment: the systematic review assessed that there is no increase in complication rate due to the presence of the cantilever.

Use of short implants (6 mm) in a single-tooth replacement: a 5-year follow-up prospective randomized controlled multicenter clinical study.

OBJECTIVE To evaluate prospectively clinical and radiographic outcomes of 6- or 10 mm-long implants with moderately rough surface (SLA(®) ) loaded within 7 weeks from installation and supporting single crowns in the posterior regions in the course of 5 years of loading. MATERIAL AND METHODS Sixty implants with a moderately rough surface, 30 tests (6 mm long, 4.1 mm in diameter) and 30 controls (10 mm long, 4.1 mm in diameter), were placed in posterior regions in 45 patients. After 6 weeks, impressions were taken and the implants were restored with a single fixed prosthesis made with gold-palladium alloy and porcelain. Survival rate and marginal bone loss were evaluated yearly. The clinical crown/implant ratio was calculated. RESULTS During the follow-up period, five implants, four tests and one control, were lost. Of the four test implants, one was lost before loading, two between the 2nd and the 3rd years, and one during the 4th year of the follow-up period. The control implant was lost during the first year of function. Consequently, after 5 years of follow-up, a survival rate of 86.7% and 96.7% was observed at the test and control sites, respectively. CONCLUSION The results of this study showed that 6-mm-long implants supporting single crowns loaded within 7 weeks from installation lose a small amount of marginal bone during 5 years of functional loading, similar to that of 10-mm-long implants. However, a higher degree of implant loss was recorded at the short implants, probably due to the fracturing of the surrounding bone.

Small-diameter titanium Grade IV and titanium–zirconium implants in edentulous mandibles: three-year results from a double-blind, randomized controlled trial

OBJECTIVE The aim of this study was to compare crestal bone-level changes, soft tissue parameters and implant success and survival between small-diameter implants made of titanium/zirconium (TiZr) alloy or of Grade IV titanium (Ti) in edentulous mandibles restored with removable overdentures. MATERIALS AND METHODS This was a randomized, controlled, double-blind, split-mouth multicenter clinical trial. Patients with edentulous mandibles received two Straumann bone-level implants (diameter 3.3 mm), one of Ti Grade IV (control) and one of TiZr (test), in the interforaminal region. Implants were loaded after 6-8 weeks and removable Locator-retained overdentures were placed within 2 weeks of loading. Modified plaque and sulcus bleeding indices, radiographic bone level, and implant survival and success were evaluated up to 36 months. RESULTS Of 91 treated patients, 75 completed the three-year follow-up. Three implants were lost (two control and one test implant). The survival rates were 98.7% and 97.3%, and the mean marginal bone level change was -0.78 ± 0.75 and -0.60 ± 0.71 mm for TiZr and Ti Grade IV implants. Most patients had a plaque score of 0 or 1 (54% for test and 51.7% for control), and a sulcus bleeding score of 0 (46.1% for test and 44.9% for control). No significant differences were found between the two implant types for bone-level change, soft tissue parameters, survival and success. CONCLUSIONS After 36 months, similar outcomes were found between Ti Grade IV and TiZr implants. The results confirm that the results seen at 12 months continue over time.

Design and validation of a DNA-microarray for phylogenetic analysis of bacterial communities in different oral samples and dental implants

The quali-quantitative characterization of the oral microbiota is crucial for an exhaustive knowledge of the oral ecology and the modifications of the microbial composition that occur during periodontal pathologies. In this study, we designed and validated a new phylogenetic DNA-microarray (OralArray) to quickly and reliably characterize the most representative bacterial groups that colonize the oral cavity. The OralArray is based on the Ligation Detection Reaction technology associated to Universal Arrays (LDR-UA), and includes 22 probe sets targeted to bacteria belonging to the phyla Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, Fusobacteria, and Spirochaete. The tool is characterized by high specificity, sensitivity and reproducibility. The OralArray was successfully tested and validated on different oral samples (saliva, lingual plaque, supragingival plaque, and healing cap) collected from 10 healthy subjects. For each specimen, a microbial signature was obtained, and our results established the presence of an oral microbial profile specific for each subject. Moreover, the tool was applied to evaluate the efficacy of a disinfectant treatment on the healing caps before their usage. The OralArray is, thus, suitable to study the microbiota associated with various oral sites and to monitor changes arising from therapeutic treatments.

Comparison of Cemented vs Screw-Retained, Customized Computer-Aided Design/Computer-Assisted Manufacture Zirconia Abutments for Esthetically Located Single-Tooth Implants: A 10-Year Randomized Prospective Study

PURPOSE To compare the clinical outcomes of screw-retained vs cemented single crowns supported by customized zirconia abutments on implants. MATERIALS AND METHODS Thirty-two patients received implant-supported (Regular Neck, Tissue-Level, Straumann AG), single-tooth restorations with customized zirconia abutments in the anterior areas. Participants were randomly assigned to the screw-retained (full-crown abutment [FCA]) group or the cemented (zirconia crown [ZrC]) group and followed up over a 10-year period. Prosthetic and biologic complications, marginal bone level (MBL), mucosal recession, and pink and white esthetic scores (PES and WES, respectively) were evaluated. RESULTS AND CONCLUSION There were no implant failures during the study period; after 10 years, 94% of crowns were functional. Prosthetic complications were recorded in both groups (three FCA and two ZrC), and no significant difference was found (P = .65). Two cases of mucositis were recorded, one in each group. Esthetic outcomes were assessed using PES and WES scores. MBL was 0.95 mm in the ZrC group and 0.82 mm in the FCA group, with no significant difference between groups. These encouraging preliminary results need to be confirmed with long-term follow-up on larger study samples.

Histological evaluation of the peri-implant tissues of three human-retrieved Straumann implants

The most frequently-used histological parameters to define dental implant osseointegration include bone-to-implant contact and quantitative and qualitative assessments of the surrounding tissue (rate of mineralized/non-mineralized tissue and proportion of lamellar and woven bone compared to soft tissue or bone marrow). The aim of this paper was to present the histological features of the bone tissue surrounding three well-functioning Straumann SLA and SLActive implants placed in two patients after 12 and 60 months of loading. The percentage of osseointegration ranged from 66.4% and 71.9% for SLA surfaces, to 88.3% for the SLActive implant. Such results confirm that osseointegration occurs with high rates of bone-to-implant contact in humans, and that implants can be similarly clinically successful, although they show different bone-to-implant contact values.