Libros

Purpose: Severe anterior maxillary atrophy offers few implant-supported rehabilitation solutions to Quad Zygoma characterized by a wide anterior cantilever. One of the possible alternatives to consider before the quad zygoma is the extra-long nasal/trans-nasal implant placement. This retrospective multicentric study shows the predictability of nasal/transnasal implant placement in patients affected by severe anterior maxilla atrophy, with residual anatomical features that indicate this surgery. This specific remote anchorage can often be safely involved in immediate loading with other remote anchorages, such as zygoma and pterygoid implants. In this rehabilitation, it’s mandatory to reduce the instability of the frameworks and mechanical stress that could unfavorably affect the implant's prognosis due to the overloading derived from anterior bending. Materials and  Methods: In this retrospective multicentric study, 52 nasal or trans-nasal implants were inserted in 31 atrophic anterior maxillas (Cawood and Howell's class V-VI). All implants were successful after the healing period; even if 27 nasal implants reached an insertional torque equal to or greater than 50 n/cm2, the threshold value estimated to be able to support an immediate load. Result: All 52 implants were successful, so the proportion of success was 100%, with a 97.5% one-sided confidence interval of 88.8-100%. The success rate is achieved only if at least two of the following criteria are met: 1) a greater torque than 50 Ncm as a minimum sufficient condition to plan immediate loading; 2) after a healing period of 16 weeks, the secondary stability is clinically and radiographically evaluated to exclude possible coronal bone resorption: this condition allows the successive prosthetic finalization; 3) the possibility of carrying out a full arch rehabilitation with minimal anterior spread. Insertion torque was <50 Newton centimeters (Ncm) in 14 patients (45%) and 50 Ncm in 17 (55%). Mechanical load was delayed in the former and immediate in the latter. The proportion of torque <50 Ncm was higher in men than in women (69% versus 28%, p=0.033). Immediate torque was not significantly affected by age. Conclusion: Although the sample is not extremely numerically significant, it conveys a clear and significant clinical, surgical indication as never before in the literature; we can state that nasal/trans nasal implants have been very useful in reducing the anterior cantilever and overcoming the anatomical limitations affecting conventional Quad Zygoma. Palabras clave: nasal implants, zygomatic implants, pterygoid implants, anterior cantilever prostheses, severe atrophy

Purpose: To compare clinical outcomes of immediate vs delayed implant loading in edentulous maxillae with full-arch fixed prostheses. Materials and Methods: Two patient groups were identified for this study: (1) the test group (TG), which included 34 patients (19 women, 15 men; mean age 56.7 years) treated with the Columbus Bridge Protocol with 4 to 6 postextractive implants loaded within 24 hours (163 implants total); and (2) the control group (CG), which included 15 patients (6 women, 9 men; mean age 59.96 years) treated with a traditional two-stage delayed loading rehabilitation using 6 to 9 implants inserted in healed sites (97 implants total). All patients were rehabilitated with full-arch fixed prostheses in the maxilla. Results: At the 10-year follow-up, no difference in the implant cumulative survival rate between the TG (93.25%) and CG (94.85%) was found. Mean bone loss was significantly lower in the TG (mean: 2.11 mm) compared to the CG (mean: 2.65 mm). All original prostheses were maintained and functioning satisfactorily. Conclusion: Maxillary full-arch immediate loading represents a valid alternative to the traditional delayed loading rehabilitation.

Purpose: The aim of this study was to analyze through a three-dimensional finite element analysis (3D-FEA) stress distribution on four implants supporting a fullarch implant-supported fixed prosthesis (FFP) using different prosthesis designs. Materials and Methods: A 3D edentulous maxillary model was created and four implants were virtually placed into the maxilla and splinted, simulating an FFP without framework, with a cast metal framework, and with a carbon fiber framework. An occlusal load of 150 N was applied, stresses were transmitted into peri-implant bone, and prosthodontic components were recorded. Results: 3D-FEA revealed higher stresses on the implants (up to +55.16%), on peri-implant bone (up to +56.93%), and in the prosthesis (up to +70.71%) when the full-acrylic prosthesis was simulated. The prosthesis with a carbon fiber framework showed an intermediate behavior between that of the other two configurations. Conclusion: This study suggests that the presence of a rigid framework in full-arch fixed prostheses provides a better load distribution that decreases the maximum values of stress at the levels of implants, prosthesis, and maxillary bone.

Purpose: The aim of this split-mouth, double-blind, randomized study is to evaluate if pulsed electromagnetic fields treatment can improve swelling and pain management after a full-arch immediate loading implant surgery. Materials and methods: Eleven patients were selected for the study. Each patient received four implants in the upper or lower jaw using distal tilted implants and underwent a full-arch immediate loading rehabilitation. After surgery two pulsed electromagnetic fields (PEMF) devices were applied on the right and the left cheek of each patient. Randomly one PEMF device was switched on (test side), applying the other one as a placebo (control side). 48 hours after surgery clinicians estimated the postoperative swelling through photographic documentation, comparing the condition prior and after surgery, while pain was assessed using a verbal rating scale. Patient's comfort degree in relation to PEMF devices was analyzed by questionnaires using a numerical rating scale. Results: No statistically significant difference was observed between the test side and the control one as regards to swelling and pain (p>0.05). Most of patients did not present swelling or pain 48 hours after surgery, without distinction between PEMF device activated and not. Variable outcomes emerged from comfort evaluation. Conclusion: Within the limits of this study, PEMF does not reduce postoperative swelling and pain after immediate loading implant surgery. Palabras clave: immediate loading, implant surgery, pulsed electromagnetic field, PEMF, postoperative swelling, pain

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.

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 study's observation period and were functioning satisfactorily at each patient's 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 study's 6-year follow-up period.

Background: Reducing the risk of overloading is mandatory to achieve a predictable osseointegration in immediate loading protocols. Purpose: The aim of this study was to analyse through a three-dimensional Finite Element Analysis (3D-FEA) stress distribution on four implants supporting a full-arch implant-supported fixed bridge (FFB) using different prosthesis design. Materials and Methods: A 3-D edentulous maxillary model was created using a customized computer software. Four implants were virtually placed into the maxilla and splinted with a FFB of 12 masticatory units. 3 different configurations were evaluated: (1) full acrylic resin prosthesis without framework, (2) acrylic resin veneering material with cast metal framework, (3) acrylic resin veneering material with a carbon fibre framework. An occlusal load of 150 N was applied on the left most distal portion of the bridge and stresses transmitted into peri-implant bone, to the implants and to the prosthodontic components were recorded. Results: 3D-FEA revealed higher stresses on the implants (up to +58,27%), on peri-implant bone (up to +56,93%) and in the prosthesis (up to +91,43%) when the full-acrylic denture was simulated. Conclusions: FEA simulating a maxillary rehabilitation revealed that FFBs endowed with a stiff framework decrease stresses on implants, prosthesis and on the peri-implant bone providing a better load distribution compared with all-acrylic prostheses. Palabras clave: Dental implants, Framework, Dental materials, Finite Element Analysis, In vitro study, Prosthodontics

Introduction: In implant prosthodontics, 50% of the errors generally encountered relate to the techniques used in implant impression and cast contruction. The remaining 50% of errors are generated by inaccurate laboratory procedures. The current dental literature reports conflicting results regarding the best material and the best technique to obtain a faithful reproduction of the position of the implants in an edentulous arch. Objectives: The aim of this in vitro study was to evaluate by an optical microscope the accuracy of the dental impressions made with 7 different techniques in full-arch rehabilitation dental implant rehabilitations. Materials and methods: A cast metal framework was realized using a master cast representing a superior jaw in which 4 implants were inserted at th elevel of the canines and of the first molars. Then implant nalogues were screwed to the metal framework and a simplified master cast was realized. This master cast was used for all the tests subsequently described. Impressios of the master cast have een taken using different materials and techniques: Impregum (polyether) + open tray technique (OTI); Impregum (polyether) + closed tray technique (CTI); Impregum (polyether) + open tray splintied technique (OTIS); Ramitec (polyether) + open tray technique (OTR); Ramitec (polyether) + closed tray technique (CTR); Ramitec (polyether) + open tray splinted technique (OTSR); BF plaster (plaster dental impression) + open tray technique (PLASTER). For each of these techniques 5 impressions of the master cast have been taken. Standard plastic impression trays provided with rimming were used. A special device was used to standardaze the force exerted during the impression and the direction of the impression tray. Casts have been realized connecting abutment analogues into the impressions. The accuracy of the framework was evaluated by the "one screw test" or Sheffield's test, screwing the metal framework previously realized on the 35 casts. An optical microscope (Smartscope MVP) with a 120x magnification was used to measure the accuracy of the interface between the abutment analogs incorporated in the casts and the metal framework. For each cast 8 measurements were taken: 4 screwing the framework at the level of the implant 26 and 4 screwing the framework at the level of the implant 16. Statistical analysis: For each of the 35 models acerage values of deviation compared to the master cast were obtained when screwing the stiff framework according to the Sheffield's test. This information was subsequently compared with the respective average values of the master model using a T-test to a sample (one sample T-test). Results: The casts made with the techniwues PLASTER (0.077±0.033μm, p=0.221), OTI (0.095±0.042μm, p=0.111) and OTSR (0.140±0.080μm, p=0.078) did not show a significant difference compared to the master model (0.056±0.047μm). Considering both the mean values compared to the master cast and the standard deviation of these three techniques, respectively V=0.43, V=0.44, V=0.57 the models obtained with plaster resulted the most similar to the master cast. Conclusion: 1) Closed tray techniques were the least reliable; 2) The splinting of impression copings with acrylic resin did not improve accuracy; 3) The association of an open tray technique with a stiff material (PLASTER) exhibited the best accuracy. Palabras clave: impression materials, impression techniques, implant rehabilitations

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. Int J Prosthodont 2014;27:15-25. doi: 10.11607/ijp.3785

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.