Effect of Si addition on Ca- and P-impregnated implant surfaces with nanometer-scale roughness: an experimental study in dogs

Objectives: To investigate the effect of Si addition on a nanometer-scale roughness Ca and P implant surfaces in a canine tibia model by biomechanical and histomorphometric evaluations. Material and methods: The implant surfaces comprised a resorbable media CaP microblasted (control) and a CaP resorbable media + silica-boost microblasted (experimental) surfaces. Surfaces were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and optical interferometry (IFM) down to the nanometric level. The animal model involved the bilateral placement of control (n = 24) and experimental surface (n = 24) implants along the proximal tibiae of six dogs, remaining in vivo for 2 or 4 weeks. After euthanization, half of the specimens were torquedto- interface failure, and the other half was subjected to histomorphologic and bone-to-implant contact (BIC) evaluation. Torque and BIC statistical evaluation was performed by the Friedman test at 95% level of significance, and comparisons between groups was performed by the Dunn test. Results: IFM and SEM observations depicted comparable roughness parameters for both implant surfaces on the micrometer and nanometer scales. XPS analysis revealed similar chemical composition, except for the addition of Si on the experimental group. Torque-to-interface failure and BIC mean values showed no significant differences (P = 0.25 and 0.51, respectively) at both 2- and 4-week evaluation points for experimental and control groups. Early bone healing histomorphologic events were similar between groups. Conclusions: The experimental surface resulted in not significantly different biomechanical fixation and BIC relative to control. Both surfaces were biocompatible and osseoconductive.

Implant-Supported Prosthesis Misalignment Related to the Dental Arch: A 14-Year Clinical Follow-up

The purpose of this study was to warn the dental community about a possible problem in function with partial implant-supported prostheses used for long periods. The misalignment between natural teeth and the implant-supported prosthesis on teeth 11 and 12, observed in a 14-year clinical follow-up, illustrates the fact. The metal-ceramic crowns were placed in 1995 after a rigorous occlusal adjustment. Evaluations were made at 4, 6, 9, and 14 years, when it was noticed that the restorations were positioned palatally and extruded in comparison with the natural teeth. After 9 years, a greater discrepancy was noticed, with anterior occlusion and esthetic changes. The possible causes have been discussed: occlusal problems, parafunctional habits, and natural movement. The first 2 options were discarded after clinical analysis and diagnosis. Therefore, the natural movement probably deriving from an interaction of mechanical and genetic factors might have been the cause. The implants do not have periodontal ligaments but rather ankylosis, so they do not suffer those movements. This case emphasizes the need to inform patients that implants can last more than 10 years in function, but this is not the case with restorations, which lose function and esthetics and must be replaced.

Deformation of Implant Abutments After Framework Connection Using Strain Gauges

When a cylinder is connected to an abutment it is expected that abutment and cylinder will be subjected to compression forces throughout their periphery because of the clamping force exerted by the screw. The deformation resultant of this compression should be measurable and uniform along the periphery of the abutment. Considering that multiple retainers connected to each other can affect the fit of a framework, as well as the use of different alloys, it is expected that the abutments will present different levels of deformation as a result of framework connection. The aim of this study was to evaluate the deformation of implant abutments after frameworks, cast either in cobalt-chromium (CoCr) or silver-palladium (AgPd) alloys, were connected. Samples (n = 5) simulating a typical mandibular cantilevered implant-supported prosthesis framework were fabricated in cobalt-chromium and silver-palladium alloys and screwed onto standard abutments positioned on a master-cast containing 5 implant replicas. Two linear strain gauges were fixed on the mesial and distal aspects of each abutment to capture deformation as the retention screws were tightened. A combination of compressive and tensile forces was observed on the abutments for both CoCr and AgPd frameworks. There was no evidence of significant differences in median abutment deformation levels for 9 of the 10 abutment aspects. Visually well-fit frameworks do not necessarily transmit load uniformly to abutments. The use of CoCr alloy for implant-supported prostheses frameworks may be as clinically acceptable as AgPd alloy.

Early peri-implant endosseous healing of two implant surfaces placed in surgically created circumferential defects. A histomorphometric and fluorescence study in dogs

Objective Several implant surfaces are being developed, some in the nanoscale level. In this study, two different surfaces had their early healing properties compared in context of circumferential defects of various widths. Material and methods Six dogs had the mandibular premolars extracted. After 8weeks, four implants were placed equicrestally in each side. One acted as control, while the others were inserted into sites with circumferential defects of 1.0, 1.5 and 2.0mm wide and 5mm deep. A nano-modified surface was used on one side and a micro-rough on the other. Bone markers were administered on the third day after implant placement and then after 1, 2, 4weeks to investigate the bone formation dynamic through fluorescence analysis. Ground sections were prepared from 8-week healing biopsies and histomorphometry was performed. Results The fluorescence evaluation of the early healing showed numerically better results for the nano-modified group; however this trend was not followed by the histomorphometric evaluation. A non-significant numerical superiority of the micro-rough group was observed in terms of vertical bone apposition, defect bone fill, bone-to-implant contact and bone density. In the intra-group analysis, the wider defects showed the worse results while the control sites showed the best results for the different parameters, but without statistical relevance. Conclusion Both surfaces may lead to complete fill of circumferential defects, but the gap width has to be considered as a challenge. The nano-scale modification was beneficial in the early stages of bone healing, but the micro-rough surface showed numerical better outcomes at the 8-week final period.

The effect of implant design on insertion torque and immediate micromotion

Objectives: To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs. Material and methods: Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (901 cut at the apex, tap design); and (3) Blossomt (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 901 by a digital torque gauge. Controlled lateral loads of 10N followed by increments of 5 up to 100N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction. Results: While insertion torque increased as a function of number of turns for each design, the slope and final values increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- standard deviation [SD] = 64.1 +/- 26.8, 139.4 +/- 17.2, and 205.23 +/- 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- SD 530 +/- 57.7, 585.9 +/- 82.4, and 782.33 +/- 269.4 mm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossomt, fluted and non-fluted design groups, respectively. Conclusion: Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque.

Mechanical analysis of conventional and small diameter conical implant abutments

PURPOSE. The aim of the present study was to evaluate if a smaller morse taper abutment has a negative effect on the fracture resistance of implant-abutment connections under oblique compressive loads compared to a conventional abutment MATERIALS AND METHODS. Twenty morse taper conventional abutments (4.8 mm diameter) and smaller abutments (3.8 mm diameter) were tightened (20 Ncm) to their respective implants (3.5 x 11 mm) and after a 10 minute interval, implant/abutment assemblies were subjected to static compressive test, performed in a universal test machine with 1 mm/min displacement, at 45 degrees inclination. The maximum deformation force was determined. Data were statistically analyzed by student t test. RESULTS. Maximum deformation force of 4.8 mm and 3.8 mm abutments was approximately 95.33 kgf and 95.25 kgf, respectively, but no fractures were noted after mechanical test. Statistical analysis demonstrated that the evaluated abutments were statistically similar (P=.230). CONCLUSION. Abutment measuring 3.8 mm in diameter (reduced) presented mechanical properties similar to 4.8 mm (conventional) abutments, enabling its clinical use as indicated. [J Adv Prosthodont 2012;4:158-61]

The influence of mandibular implant-retained overdentures in masticatory efficiency

Objective: To evaluate the masticatory efficiency of patients rehabilitated with conventional dentures (CDs) or implant-retained mandibular overdentures. Background: Despite the evident benefits of implants on mastication as assessed by subjective patient-based outcomes, the extent of implant overdenture treatment effect on food comminution is not well established. Materials and methods: A randomised clinical trial was carried out with 29 completely edentulous patients divided into two groups. The first group was rehabilitated with a mandibular overdenture retained by two splinted implants with bar-clip system, while the second group was rehabilitated with a mandibular CD. Both groups also were rehabilitated with maxillary CDs. Masticatory efficiency and patient satisfaction were assessed 3 months after denture insertion. Masticatory efficiency was evaluated through the colorimetric method with the beads as the artificial test-food. Comparisons for masticatory efficiency and patient satisfaction were performed using Student's t-test (alpha = 0.05). Results: No significant statistical difference was found for masticatory efficiency (p = 0.198). Patient overall satisfaction was significantly higher for the mandibular overdenture (p < 0.001). In addition, mandibular overdenture patients were significantly more satisfied with chewing experience (p < 0.05) and retention of the lower denture (p < 0.005). Conclusion: The results of this study suggest that mandibular overdenture significantly improves chewing experience, although limited effect on masticatory efficiency has been observed.

Effects of the etonogestrel-releasing contraceptive implant inserted immediately postpartum on maternal hemostasis: A randomized controlled trial

Introduction: The puerperium is the period of highest risk for thrombosis during a woman's reproductive life and it is an important time for initiating an effective contraceptive method in order to increase intergestational interval. Thus, the objective of the present study was to evaluated the effects of the etonogestrel (ENG)-releasing contraceptive implant inserted immediately postpartum on maternal hemostasis markers during the first six weeks of delivery. Materials and Methods: Forty healthy women aged 18 to 35 years-old were randomized to receive either the ENG-releasing implant 24-48 h after delivery (implant group; n=20) or nothing (control group) until the sixth postpartum week. Blood samples were collected at 24-48 h and at 6 weeks after delivery, and hemostatic variables, including fibrinogen, coagulation factors, protein C, free protein S, antithrombin, alpha 2-antiplasmin, plasminogen activator inhibitor 1, thrombin-antithrombin complex (TAT), prothrombin fragment (PF)1+2, and D-dimers, as well as normalized activated protein C sensitivity ratio (nAPCsr), thrombin time, activated partial thromboplastin time, and prothrombin time were evaluated. Results: Insertion of the ENG-releasing contraceptive implant did not change the physiological reduction in overall coagulation (TAT and PF1+2) and fibrinolysis (D-dimer) markers, or nAPCsr. Reductions in factors II, VII, X and fibrinogen and increases in factor V were greater in the control than in the implant group. Clotting factors remained within normal limits throughout the study. Conclusion: The ENG-releasing contraceptive implant inserted immediately postpartum did not have negative effects on physiological variations of the hemostatic system during the first 6 weeks postpartum. (C) 2012 Elsevier Ltd. All rights reserved.

Prosthetic misfit of implant-supported prosthesis obtained by an alternative section method

PURPOSE. Adequate passive-fitting of one-piece cast 3-element implant-supported frameworks is hard to achieve. This short communication aims to present an alternative method for section of one-piece cast frameworks and for casting implant-supported frameworks. MATERIALS AND METHODS. Three-unit implant-supported nickel-chromium (Ni-Cr) frameworks were tested for vertical misfit (n = 6). The frameworks were cast as one-piece (Group A) and later transversally sectioned through a diagonal axis (Group B) and compared to frameworks that were cast diagonally separated (Group C). All separated frameworks were laser welded. Only one side of the frameworks was screwed. RESULTS. The results on the tightened side were significantly lower in Group C (6.43 +/- 3.24 mu m) when compared to Groups A (16.50 +/- 7.55 mu m) and B (16.27 +/- 1.71 mu m) (P<.05). On the opposite side, the diagonal section of the one-piece castings for laser welding showed significant improvement in the levels of misfit of the frameworks (Group A, 58.66 +/- 14.30 mu m; Group B, 39.4.8 +/- 12.03 mu m; Group C, 23.13 +/- 8.24 mu m) (P<.05). CONCLUSION. Casting diagonally sectioned frameworks lowers the misfit levels. Lower misfit levels for the frameworks can be achieved by diagonally sectioning one-piece frameworks. [J Adv Prosthodont 2012;4:89-92]

Foreign Body Ingestion During Dental Implant Procedures

Two cases of swallowing of foreign material related to dental implants during dental practice are described. A conservative approach by clinical-radiographic follow-up was performed in both cases; however, one of the patients required colonoscopy under general anesthesia for the removal of the impacted foreign body from the intestinal region. These complications not only have associated economic cost but also carry the risk of malpractice litigation against the professional; thus, the surgeon was responsible for all the costs of hospital and surgery management of this case. Details of the clinical signs, radiographic examinations, type of treatment, and follow-up are presented.

Anatomical and functional evaluation of tympanoplasty using a transitory natural latex biomembrane implant from the rubber tree Hevea brasiliensis

PURPOSE: To compare the role of transitory latex and sylastic (R) implants in tympanoplasty on the closure of tympanic perforations. METHODS: A randomized double-blind prospective study was conducted on 107 patients with chronic otitis media submitted to underlay tympanoplasty and divided at random into three groups: control with no transitory implant, latex membrane group, and sylastic (R) membrane group. RESULTS: Greater graft vascularization occurred in the latex membrane group (p<0.05). Good biocompatibility was obtained with the use of the latex and silicone implants, with no effect on the occurrence of infection, otorrhea or otorragy. CONCLUSION: The use of a transitory latex implant induced greater graft vascularization, with a biocompatible interaction with the tissue of the human tympanic membrane.

Mini-implant insertion based on tooth crown references: a guide-free technique

Mini-implant insertion requires accurate surgical technique. This study shows an insertion technique using only tooth crown references; its scientific basis is evaluated radiographically. The sample consisted of 213 inter-radicular septa, evaluated in 53 bitewing radiographs. The proximal contour of adjacent tooth crowns was used to define septum width. The midpoint of the septum width was linked to the interdental contact point to determine septum midline. The distances from septum midline to "mesial and distal teeth were measured to evaluate the septum midline centralization degree in two different septum heights. The difference between mesial and distal distances represented the septum midline deviation degree. The mesial and distal distances were compared by t-tests, and the septum midline deviation was correlated with septum height using Pearson's correlation test. The mesial and distal distances were not statistically different in the midpoint of the septum height, but they were different at the apical septum height. There was a moderate correlation (r = 0.45) between septum midline deviation and septum height. The tooth crown references evaluated on interproximal radiographs determine a high centralization degree of the septum midline on which the insertion site could be defined. The greater centralization degree was observed at the coronal septum area.

Cochlear implant in postlingual children: functional results 10 years after the surgery

The benefits of cochlear implants (CI) for communication skills are obtained over the years. There are but a few studies regarding the long-term outcomes in postlingual deaf children who grew up using the electronic device. Aim: To assess the functional results in a group of postlingual children, 10 years after using a CI. Methods: Ten postlingual deaf children, implanted before 18 years of age, participated in this study. We assessed: sentence recognition and speech intelligibility. We documented: device use and function and the patient's academic/occupational status. Study design: series. Results: The mean scores were 73% for sentence recognition in silence and 40% in noise. The average write-down intelligibility score was 92% and the average rating-scale intelligibility score was 4.15. There were no cases of device failure. Regarding educational/vocational status, three subjects graduated from the University. Five quit education after completing high school. Eight subjects had a professional activity. Conclusion: This study showed that cochlear implantation is a safe and reliable procedure. The postlingual profoundly hearing-impaired children after 10 years of CI use developed satisfactory levels regarding speech perception and intelligibility, and completed at least high school and were inserted in the labor market. Clinical Trials Registry: NCT01400178.

The Role of Keratinized Mucosa in Peri-Implant Health

Objective: To evaluate the role of keratinized mucosa around dental implants, correlating with other clinical parameters related to the success of dental implants. Design: Cross-section. Setting: Institutional tertiary referral hospital. Patients: A total of 202 dental implants fixed in the cleft area of 109 patients with cleft lip and/or palate were evaluated. Interventions: The evaluated clinical parameters were probing depth and gingival and plaque indexes on the buccal surface (three sites). Main Outcome Measures: All clinical parameters were correlated with the width of keratinized mucosa around the implants. Results: The largest probing depths were detected when the width of keratinized mucosa was 2 mm or more, with a statistically significant difference between the means of the probing depth and keratinized mucosa width. Conclusion: Even though the present results suggest that peri-implant health can be observed in areas with keratinized mucosa width under 2 mm provided an adequate oral hygiene control is performed, longitudinal randomized studies are necessary to analyze the relationship between the width of keratinized mucosa and the health of peri-implant tissues.

STUDY ON IMPLANT STABILITY IN CEMENTLESS TOTAL KNEE ARTHROPLASTY

Objetives: Determine the stability of tibial and femoral components of 20 cementless knee arthroplasties with rotating platform. Methods: The 20 patients (20 knees) underwent an analysis of dynamic radiographs with an image amplifier and maneuvers of varus and valgus which were compared to static frontal and lateral radiographs of the knees and analyzed by two experienced surgeons in a double-blind way. Results: We could observe in this study that both methods showed very similar results for the stability of the tibial and femoral components (p<0.001) using the Kappa method for comparison. Conclusion: The tibial component was more unstable in relation to the femoral component in both static and dynamic studies. Level of Evidence IV, Case Series.