Maria Menini

Immediate function with fixed implant-supported maxillary dentures: A 12-month pilot study

STATEMENT OF PROBLEM Immediate occlusal loading of dental implants in the edentulous mandible has proven to be an effective, reliable, and predictable procedure. There is little long-term data available on similar treatments in the edentulous maxilla. PURPOSE The purpose of this study was to evaluate the 12-month implant survival after immediate loading of 4 to 6 implants with fixed screw-retained prostheses in edentulous maxillae. MATERIAL AND METHODS Twenty-one patients, edentulous or with remaining teeth to be extracted in the maxilla, received 4 to 6 implants (n=111). The patients were restored with screw-retained fixed provisional prostheses supported by palladium-alloy frameworks within 24 hours after surgery. Insertion torques for implants were at least 40 Ncm. Implants, grouped as tapered or cylindrical screws, were placed in healed bone or extraction sockets. Implants were also classified as either vertical or off-angle. Definitive prostheses were placed after a mean healing time of 18 weeks. Radiographic examinations were made at the time of placement of provisional prostheses and 12 months later. Between-groups bone resorption was compared using 2-way ANOVA (alpha=.05). RESULTS The mean follow-up time for all of the patients was 20 months (range, 13 to 28 months). The cumulative implant survival rate at the 12-month follow-up visits (after surgery) was 92.8%; the prostheses survival rate was 100%. No significant differences were found between the survival of tapered or cylindrical screw-type implants placed in postextraction sockets versus those in healed edentulous sites or between vertical and off-angle placed implants. Eight implants failed during the first 3 months, 5 of which were the most distal implants. The mean reduction in marginal bone height over the 12-month observation period was 0.84 mm (CI 95%; 0.68-0.99 mm). CONCLUSIONS In this study with 12-month follow-up, 4 to 6 implants were sufficient to successfully support fixed implant screw-retained prostheses in the edentulous maxillae of 21 patients.

Tilted Implants in the Immediate Loading Rehabilitation of the Maxilla: A Systematic Review

Tilted implants have been proposed as an alternative to traditional protocols in the rehabilitation of edentulous maxillae. The aim of this meta-analysis was to evaluate the outcomes of upright and tilted implants supporting full-arch fixed dentures for the immediate rehabilitation of edentulous maxillae, after at least 1 year of function. An electronic search of databases and a hand search of relevant journals in oral implantology were performed according to PRISMA guidelines through August, 2011. The literature search yielded 1,069 articles. Eleven articles were available for analysis. A total of 1,623 implants (778 tilted, 845 upright) were inserted into the maxillae of 324 patients. Seventeen tilted (2.19%) and 16 upright implants (1.89%) failed during the first year. No significant difference in failure rate was found between tilted and upright implants (p value = 0.52). Marginal bone level results were obtained from 6 studies. A non-significant mean difference between tilted and upright implants was found with regard to bone loss. Tilted implants demonstrated a favorable short-term prognosis in full-arch immediate loading rehabilitations of the maxillae. Randomized long-term trials are needed to better elucidate long-term success of tilted vs. upright-positioned implants.

Sinus floor elevation using osteotomes or piezoelectric surgery

The aim of this paper is to describe a technique for sinus floor augmentation with a 1-step crestal approach where the residual bone is ≤ 7.5mm. 36 implants were installed in 25 patients in the atrophic posterior maxilla immediately after sinus floor elevation. Sinus floor elevation was performed with a crestal approach using either osteotomes and burs or piezosurgery. Standardized intraoral radiographs were taken prior to surgery and 1 year after surgery. The mean residual bone height was 5.61 mm (range 3-7.5mm). The mean gain of sinus elevation was 6.78 mm (range 3.5-10mm) at 1 year after surgery. Two patients dropped out of the study. Of the 23 patients completing the study, one implant failed, whilst the remaining 33 implants were stable 12 months after surgery (cumulative survival rate 97%). A statistically significantly higher bone height was achieved with tapered implants compared with cylindrical implants (P<0.05). No statistically significant differences were found in bone level using osteotomes or piezosurgery. Piezosurgery was considered to provide less discomfort for the patient and greater convenience for the surgeon.

Peri-implantitis: a systematic review of recently published papers.

PURPOSE This systematic review considers possible etiologic factors and definitions of peri-implantitis as reported in the recent literature. MATERIALS AND METHODS An electronic search of databases plus a hand search of the most relevant journals published between January 2005 and September 2012 were performed. RESULTS The electronic and manual searches yielded 640 and 14 titles, respectively. From the independent doublecheck of the titles and abstracts, 24 full texts were downloaded (18 clinical studies and 6 animal studies). After reading the full texts, 10 articles (4 clinical studies and 6 animal studies) were included in this review. None of the human articles selected provided sufficient evidence to address the research question, and no human clinical evidence is available to support a cause-effect relationship between peri-implantitis and bacterial accumulation and/or occlusal overload. The animal literature is also not unanimous regarding a specific peri-implantitis etiology. However, a correlation between periodontitis and smoking histories was cited as contributing to a higher incidence of peri-implantitis. CONCLUSION The available scientific literature is characterized by an absence of a unanimous consensus regarding the etiology of peri-implantitis and its specific relationship to periodontitis. Furthermore, both the choice of the term peri-implantitis and its definition remain controversial.

Immediate Versus Delayed Loading of Dental Implants in Edentulous Patients’ Maxillae:: A 6-Year Prospective Study

PURPOSE This study compared the surgical protocol efficacy of immediate and delayed implant loading in edentulous maxillae opposed by natural or restored mandibular dentitions over an observational period of 6 years or longer. The selected outcome determinants included individual implant survival data, progressive measurements of peri-implant bone resorption, prosthodontic survival and success data, and report of complications. MATERIALS AND METHODS A convenience sample of 49 patients requiring fixed implant-supported maxillary prostheses was split into two groups. The test group (34 patients) was treated according to the Columbus Bridge Protocol, which prescribes the insertion of four to six implants, including distally tilted implants, and load within 24 hours. The control group (15 patients) was treated via a two-stage surgical protocol of 6 to 9 straight implants that were loaded a mean 8.75 months after stage-one implant surgery. Two hundred sixty implants (test: n = 163, control: n = 97) were placed, and all subjects were ultimately treated with screw-retained full-arch prostheses. RESULTS Two patients dropped out (one in the test group and one in the control group) by the time of the scheduled sixth annual visit. The other patients were followed up for 75.2 months (range: 72 to 90 months). At the 6-year follow-up, no differences in implant cumulative survival rates were found between groups. Significantly less bone loss was found in the test group (mean: 1.62 mm) compared with the control group (mean: 2.44 mm). All of the original prostheses were maintained throughout the studys observation period and were functioning satisfactorily at each patients last recall appointment. CONCLUSION Patients who received immediate and delayed implant loading in their edentulous maxillae demonstrated similar survival outcomes. However, less marginal bone loss was recorded around the immediately loaded implants over the studys 6-year follow-up period.

Shock Absorption Capacity of Restorative Materials for Dental Implant Prostheses: An In Vitro Study

PURPOSE To measure the vertical occlusal forces transmitted through crowns made of different restorative materials onto simulated peri-implant bone. MATERIALS AND METHODS The study was conducted using a masticatory robot that is able to reproduce the mandibular movements and forces exerted during mastication. During robot mastication, the forces transmitted onto the simulated peri-implant bone were recorded using nine different restorative materials for the simulated single crown: zirconia, two glass-ceramics, a gold alloy, three composite resins, and two acrylic resins. Three identical sample crowns for each material were used. Each crown was placed under 100 masticatory cycles, occluding with the flat upper surface of the robot to evaluate the vertical forces transmitted. Two-way analysis of variance was used. Alpha was set at .05. RESULTS The statistical evaluation of the force peaks recorded on the vertical z-axis showed mean values of 641.8 N for zirconia; 484.5 N and 344.5 N, respectively, for the two glass-ceramics; 344.8 N for gold alloy; 293.6 N, 236 N, and 187.4 N, respectively, for the three composite resins; and 39.3 N and 28.3 N, respectively, for the two acrylic resins. Significant differences were found between materials (P < .0001), except for the comparison between gold alloy and one of the glass-ceramics. CONCLUSION Composite and above all acrylic resin crowns were more able to absorb shock from occlusal forces than crowns made of zirconia, ceramic material, or gold alloy.

Biological and mechanical characterization of carbon fiber frameworks for dental implant applications

OBJECTIVES The aim of the present study was to investigate the biocompatibility and mechanical characteristics of dental implant frameworks made of carbon fiber composite. METHODS The biocompatibility of intact samples and fragments was evaluated by cell count and MTT test according to EN-ISO 10993-5:2009 directions. Destructive and non-destructive mechanical tests were performed in order to evaluate: porosity, static and dynamic elastic modulus of carbon fiber samples. These tests were conducted on different batches of samples manufactured by different dental technicians. The samples were evaluated by optical microscope and by SEM. A compression test was performed to compare complete implant-supported fixed dentures, provided with a metal or carbon fiber framework. RESULTS Carbon fiber intact and fragmented samples showed optimal biocompatibility. Manufacture technique strongly influenced the mechanical characteristics of fiber-reinforced composite materials. The implant-supported full-arch fixed denture provided with a carbon fiber framework, showed a yield strength comparable to the implant-supported full-arch fixed denture, provided with a metal framework. SIGNIFICANCE Carbon fiber-reinforced composites demonstrated optimal biocompatibility and mechanical characteristics. They appear suitable for the fabrication of frameworks for implant-supported full-arch dentures. Great attention must be paid to manufacture technique as it strongly affects the material mechanical characteristics.

Factors affecting the outcome in the immediate loading rehabilitation of the maxilla: a 6-year prospective study.

This prospective study reports the 6-year outcomes for patients rehabilitated with an immediate loading protocol of the maxilla (Columbus Bridge Protocol). In this study, 164 implants were inserted in 37 patients and loaded within 24 to 36 hours. Four implants failed during the first 6 months. At the 6-year follow-up, a mean bone loss of 1.52 mm was found. Significantly (P < .0083) less bone loss was found next to tapered implants compared with cylindric implants and next to machined collar implants compared with full acid-etched implants (P < .0083). No significant differences in bone loss were found in tilted versus upright implants or in mesial versus distal implant sites. In addition, there were no significant differences relating to either the degree of abutment angulation or the reason for tooth loss.

Adhesive strength of the luting technique for passively fitting screw-retained implant-supported prostheses: an in vitro evaluation.

PURPOSE This in vitro study evaluated the adhesive strength of a technique to lute implant cylinders to metal frameworks in implant-supported prostheses and ensure a good passive fit. MATERIALS AND METHODS Different height samples were tested: In group 1, implant cylinders were 5 mm long; in group 2, they were 10 mm long. A universal testing machine (Instron) was used to perform pullout tests. RESULTS The luting technique provided enough adhesive strength for clinical use with greater adhesive strength in group 2 (mean pull-out strength: 2.85 kN in group 1 versus 3.79 kN in group 2). CONCLUSIONS The luting technique provides enough adhesive strength for clinical use. Moreover, specimens with a larger surface for adhesion demonstrated higher adhesive strength compared with shorter specimens.

Influence of Different Surface Characteristics on Peri-implant Tissue Behavior: A Six-Year Prospective Report.

PURPOSE The aim of this study was to evaluate the behavior of hard and soft tissue around implants with different surface treatments. MATERIALS AND METHODS Eight patients were identified for this study. Each patient received at least 2 implants (1 control, 1 test) into an edentulous quadrant, for a total of 10 pairs of implants. Two types of implants were used: hybrid implants (control) with a dual acid-etched surface in their apical portion and a machined coronal part, and test implants with an acid-etched surface throughout their entire length. Standardized periapical radiographs were taken at baseline, 3 months, 6 months, and 1 year post implant placement and then annually until the 6-year follow-up. Bleeding on probing (BOP) and Plaque Index (PI) were recorded annually. Probing depth (PD) was recorded at the 6-year follow-up. RESULTS Moderate crestal bone remodeling was observed during the 1-year postimplant placement evaluation (P=.001), and test implants revealed smaller marginal bone resorption (P=.030). No significant changes in bone level were observed between the 1-year and the 6-year follow-up appointments, and a significantly smaller bone resorption was found at test implants. No statistically significant differences in bone resorption were found between maxilla and mandible. No statistically significant differences were detected between test and control implants for BOP, PI, or PD. CONCLUSIONS The preliminary results suggest that implant surface characteristics might affect the bone remodeling phase subsequent to the surgical trauma. However, once osseointegration was established, implant surfaces did not affect bone maintenance over time. Implant surfaces did not affect soft tissue behavior. The results of this pilot study need to be confirmed in a study with a larger sample size and over a longer time frame.