The International Journal of Oral & Maxillofacial Implants, 01/2005

Purpose: The aim of this study was to evaluate the surface chemistry and the microhardness at the implant-bone interface using a recently developed collagen-coated titanium implant in a short-term rabbit model. Materials and Methods: Surface chemistry was evaluated by x-ray photoelectron spectroscopy (XPS), while in vivo studies involved 4-week implants mid-diaphysis in the lateral femurs of adult male rabbits. After conventional embedding and evaluation of histologic sections, the resin-embedded blocks containing the implanted screws were used to measure bone hardness by means of an indentation test. Results: Decomposition of the C1s peak obtained by XPS analysis confirmed that surface-immobilized collagen retained all the molecular features of the control, nonimmobilized reference. As to microhardness measurement, newly formed bone at the collagen-coated-implant/bone interface was significantly harder than bone at the interface of the uncoated control implant and bone. Discussion: These results suggested that collagen coating significantly improves bone maturation and mineralization at the interface in comparison with uncoated commercially pure titanium. Surface modification of titanium implants by collagen coating has recently been discussed as a promising approach to the biochemical modification of implant surfaces. The present results support previous histologic findings and demonstrated that the biomolecular layer linked over the titanium implant can increase the bone healing rate, at least in this animal model. Conclusions: The present microhardness measurement at the bone-implant interface showed that collagen coating can significantly improve bone maturation and mineralization at the interface in comparison with uncoated commercially pure titanium, confirming and substantiating previous findings by histomorphometric measurements from the same model.

Purpose: This study was undertaken to evaluate ion beam-assisted deposition (IBAD) of hydroxyapatite (HA) on the grit-blasted surface of endosseous dental implants 6 weeks postplacement. Materials and Methods: A total of 40 implants was placed in the tibiae of 10 New Zealand white rabbits. Twenty implants were grit-blasted only and the other 20 were grit-blasted and coated with HA by the IBAD method. After 6 weeks of healing, the rabbits were sacrificed and removal torque tests, histomorphometry, and morphometric analysis of microtomographic images were performed. Results: The HA-coated group showed significantly higher removal torque, bone-to-implant contact, and bone volume than the other group. Discussion and Conclusion: In a previous study, the authors suggested that HA coating deposited on a machined surface by the IBAD method showed results comparable to or more favorable than the results obtained with a blasted surface. This study indicated that the HA coating produced by the IBAD method was also very effective on the aluminum oxide-blasted surface, as demonstrated by the early formation of osseointegration. Morphometric analysis by microtomography showed some promise in measuring the osseointegration rate. (More than 50 references.)

Purpose: To assess the course of the stability and the failure rate of dental implants placed in the partially edentulous maxillae of minipigs. Materials and Methods: Three months after tooth removal, implants were placed in 9 minipigs. Six implants (XiVE; Friadent, Mannheim, Germany) were placed on each side of the posterior maxilla after preparation of the implant sites either by an osteotome technique or with spiral drills. Implant stability was assessed by resonance frequency analysis (RFA) at the time of placement, at second-stage surgery (which took place after a healing periods of 1, 2, 3, 4, or 5 months), and after a loading period of 6 months. Results: Implant stability was significantly influenced by the healing period (P = .007). Implant stability decreased after 1 to 3 months of healing for both of the placement techniques and increased after a healing period of 4 months. After implant site preparation by an osteotome technique, 6 of 12 immediately loaded implants, 18 of 24 implants loaded after healing periods of 1 to 3 months, and 1 of 18 implants loaded after a healing period of 4 or 5 months were lost. After implant site preparation using spiral drills, 7 of 12 immediately loaded implants, 12 of 24 implants loaded after healing periods of 1 to 3 months, and 2 of 18 implants loaded after healing periods of 4 or 5 months were lost. Broad overlapping of confidence intervals for the number of implant failures revealed that there was no relevant difference between immediate and early functional loading for either of the 2 techniques. Discussion and Conclusion: Implant loading after healing periods of 1 to 3 months did not improve implant survival compared to immediate loading in the posterior maxillae of minipigs. Not until a healing period of 4 months was reached did implant stability begin to increase. Only when functional loading was started at this point in time was maximal implant survival achieved.

To evaluate the biocompatibility and the bone-bonding strength of new titanium alloy materials treated by sandblasting and anodic oxidization, 3 cylindric test pieces having different surface roughnesses were manufactured and implanted into the diaphyses of the femurs of New Zealand white rabbits. Six weeks later, shear loading tests and histologic examination were carried out. Strong interfacial bonding strength and active new bone formation were confirmed in the peripheral area of the test pieces having a surface roughness (Ra = 2.7 µm and Ra = 4.7 µm). Judging from stable fixation to shear loading in bone tissue, it was concluded that group C (Ra = 2.7 µm) had the best surface condition of the 2 groups. Further detailed examination is required to demonstrate that the surface treatment used for group C (a micro rough surface on a macro rough surface structure) can enhance active bone formation and stable fixation in bone tissue.

Purpose: Transitional implants (TIs) were developed as a method of providing fixed provisional restorations for the implant patient who wishes to avoid removable temporary restorations during implant healing. Success of TIs depends on achieving sufficient osseointegrated bone-to-implant contact (BIC) during the provisional prosthesis phase. To date, little data are available on the degree of BIC of these implants in function. The purpose of this study was to histologically evaluate the BIC of TIs following various periods of loading. Materials and Methods: Histologic analysis of 33 immediately loaded implants from 21 patients was performed. All TIs had turned machined surfaces and were made of commercially pure titanium (grade 1). These transitional implants were in function for an average of 10.8 months (range: 6 to 27 months). Before the definitive restoration was provided, all of the TIs were removed with trephine drills and sent for hard tissue histomorphometric analysis. Results: The average percentage of BIC was 52.9% ± 13.81% (range 25.1% to 83%). Discussion: Although TIs are traditionally removed when the definitive implants are restored, the BIC and clinical integration of the TIs in the present study may suggest a change in TI protocol. Studies are indicated to examine long-term use of TIs as sole support or in conjunction with definitive implants in definitive implant-supported restorations. Conclusion: The percentage of BIC achieved with TIs was similar to that documented in the literature for conventional turned, machine-surfaced implants.

Purpose: The aim of this study was to evaluate the clinical response and safety of immediately loaded single-tooth implants placed in the posterior region of the maxilla and mandible. Materials and Methods: Single-tooth implants were placed in healed extraction sites in 20 adult patients. Temporary prefabricated acrylic resin crowns were prepared and adjusted. The crown occlusion was adjusted to obtain minimal contacts in maximum intercuspation. After 6 weeks a ceramometal or all-ceramic crown was cemented. Radiographic and clinical examinations were made at baseline and at 3, 6, and 12 months. Cortical bone response and peri-implant mucosal responses were evaluated. Results: The marginal bone level at the time of implant placement was preserved. The mean change in marginal bone level was 0.01 mm at 12 months. The mean Periotest value after 360 days was -4. The peri-implant mucosal adaptation to the anatomic form of the provisional crown resulted in a natural esthetic outcome, and a gain in papilla length was observed. One implant failure was recorded because of provisional luting cement impaction. Discussion: Clinical research has shown that immediate loading is a possible treatment modality. The immediate functional loading of implants placed in this study resulted in bone adaptation to loading. A satisfactory success rate with positive tissue responses was achieved. Conclusions: The results of this limited investigation indicated that immediate loading of unsplinted single-tooth implants in the posterior region may be a viable treatment option with an esthetic outcome.

Purpose: Implant length, implant surface area, and crown-to-root (c/r) ratio and their relationship to crestal bone levels were analyzed in 2 groups of partially edentulous patients treated with sintered porous-surfaced dental implants. Materials and Methods: One hundred ninety-nine implants were used to restore 74 partially edentulous patients with fixed prostheses. Implants were categorized according to their length (¡°short¡± versus ¡°long¡±) and estimated surface area (¡°small¡± versus ¡°large¡±). ¡°Short¡± implants had lengths of 5 or 7 mm, while ¡°long¡± implants were either 9 or 12 mm in length. ¡°Small¡± implants had estimated surface areas of = 600 mm², while ¡°large¡± implants had estimated surface areas > 600 mm². Other data collected included c/r ratio (measured on articulated diagnostic casts), whether or not the implants were splinted, and standardized sequential radiographs. Results: The mean c/r ratio was 1.5 (SD = 0.4; range 0.8 to 3.0), with 78.9% of the implants having a c/r ratio between 1.1 and 2.0. Neither c/r ratio nor estimated implant surface area (small or large) affected steady-state crestal bone levels. However, implant length and whether the implants were splinted did appear to affect bone levels. Long implants had greater crestal bone loss (0.2 mm more) than short implants; splinted implants showed greater crestal bone loss (0.2 mm more) than nonsplinted ones. These differences were statistically significant. Discussion and Conclusions: Sintered porous-surfaced implants performed well in short lengths (7 mm or less) in this series of partially edentulous patients. The data suggested that long implants and/or splinting can result in greater crestal bone loss; longer implants and splinted implants appeared to favor greater crestal bone loss in this investigation. These conclusions are, of course, specific to the implants used and would not be relevant to other implant types.

Purpose: Guided bone regenerative therapy has become a significant component of clinical implant practice. Initial reports have demonstrated success rates of implants in regenerated bone under function comparable to the success rates of implants placed in native nonregenerated host bone. This report documents the success and failure rates of osseointegrated implants placed in regenerated bone for up to 133 months in function. Materials and Methods: A retrospective analysis of a group of 607 titanium plasma-sprayed cylindric implants placed in regenerated bone, the success and failure rates of which were previously reported at 6 to 51 months in function, were assessed. Results: The implants demonstrated cumulative success rates of 97.2% for the maxilla and 97.4% for the mandible, yielding an overall cumulative success rate of 97.4% for up to 133 months in function. Discussion and Conclusions: Titanium plasma-sprayed osseointegrated implants of various diameters, lengths, and designs, utilized in a variety of clinical scenarios, demonstrated functional cumulative success rates comparable to those of implants placed in nonregenerated host bone for extended periods of time in this patient population.

Purpose: The aim of the present study was to evaluate the concept of an immediate loading protocol in the posterior maxilla and mandible through analysis of implant survival at 1 year. Materials and Methods: One year follow-up data of a multicenter study are reported. Eighty-two ITI sandblasted, acid-etched (SLA) implants in 40 patients were loaded between 0 and 11 days after implant placement (mean 4.3 ± 2.8 days). The restorations consisted of either 2 splinted crowns or a 3-unit fixed prosthesis. All restorations were put into full functional occlusion. Periapical radiographs were evaluated for changes in crestal bone level from baseline to 1 year postloading. Primary stability of the implants was checked initially and before the fitting of the definitive prosthesis. The restorations were evaluated by the practitioners for retention, stability, and esthetics. Results: Three patients' implants were not loaded because of lack of primary stability, and a fourth patient was excluded from the study because of a protocol violation (more than 4 implants were used). All 4 patients were successfully treated outside the protocol. The overall survival rate of the remaining implants at 1 year was 98.8%. The mean bone loss at 1 year was 0.52 ± 0.98 mm, which is within the reported limits of less than 1 mm (range 0.4 to 1.4 mm) loss in the first year. Discussion and Conclusion: The early results from this study indicate that early and immediate loading of 2 implants in the posterior maxilla and mandible may be suitable in selected patients. On the basis of 1 year of observation, the results appear similar to those achieved with a delayed procedure.

Computerized navigation surgery has evolved to facilitate minimally invasive procedures, the gold standard of surgery today. While flapless implant surgery may be clinically beneficial, it has generally been perceived as a blind procedure limited to straightforward cases that do not pose a risk of cortical plate perforation. The objective of this report is to describe a protocol for flapless implant placement in a completely edentulous mandible using computerized navigation surgery. The Image Guided Implantology system (IGI, DenX Advanced Dental Systems) is described. The IGI system provides real-time imaging of the dental drill and transforms flapless implant surgery into a fully monitored procedure. The highly accurate intraoperative navigation enables precise transfer of the detailed presurgical implant plan to the patient. This is particularly valuable in edentulous jaws lacking any indication of the dental arch. The accurate positioning of the implants, based on the presurgical digital plan, allows fabrication of a provisional fixed prosthesis before the implant surgery for immediate postoperative loading. This innovative protocol can enhance prosthodontic-driven placement of implants in a fully monitored flapless surgery.

Purpose: The aim of this study was to clinically evaluate immediate functionally loaded (IFL) and immediate nonfunctionally loaded (INFL) implants for various indications compared to a control group with a conventional healing period. Materials and Methods: Two hundred fifty-three patients took part in the study. A total of 702 XiVE implants (Dentsply/Friadent, Mannheim, Germany) were placed: 253 IFL implants, 135 INFL implants, and 314 controls. Results: In each of the 3 groups, 2 implants failed. For all the other implants involved, from a clinical and radiographic point of view, osseointegration was successful. Discussion: As long as the prerequisites are fulfilled, immediate functional loading and immediate nonfunctional loading are predictable techniques, not only in completely edentulous patients but also in partially edentulous patients. Conclusion: Immediate functional loading and immediate nonfunctional loading appear to be techniques that can provide satisfactory implant success rates in selected cases.

Purpose: Laboratory processing of implant-supported prostheses may alter the surface of the abutment in contact with the implant head, with potential repercussions for the interface fit. The purpose of this study was to assess changes at the implant interface of high-strength zirconia ceramic esthetic abutments with a hexagonal connection (ZiReal; 3i/Implant Innovations, Palm Beach Gardens, FL) following abutment preparation for single-tooth restorations. Materials and Methods: The depth (d) and width (w) of the titanium hexagonal portion of the abutment, the apical diameter of the abutment (D), and the rotational freedom (R) of the abutment were assessed for 20 ZiReal abutments prior to preparation (time 0) and following abutment preparation (time 1) to detect any eventual change of fit of the abutment on the top of the implant hexagon. Results: No significant differences relative to any study parameter (d, w, D, and R) were observed between time 0 and time 1 (P = .9542). Discussion and Conclusions: The hexagonal misfit of the titanium machined ZiReal abutment on the implant hexagon may be implicated in screw joint loosening. The results of this report suggest that if all laboratory steps are carefully observed, changes at the implant/ZiReal abutment do not occur. The maintenance of the original features of the ZiReal abutment may reduce the risk of screw loosening.

Purpose: The purpose of this prospective study was to compare the efficacy of prophylactic antibiotic regimens commonly used in dental implant surgery. Preoperative single-dose and long-term prophylactic antibiotic regimens were compared. Materials and Methods: This was a 2-center prospective study in which 215 patients underwent ambulatory endosseous implant placement. In the first group, 445 dental implants were placed in 125 patients after the administration of a single preoperative dose of prophylactic antibiotic with no postoperative antibiotics. In the second group, 302 dental implants were placed in 90 patients who received a preoperative dose of antibiotics and were instructed to take antibiotics postoperatively for 7 days. In both groups, 0.12% chlorhexidine pre- and postoperative mouth rinses were used. Patients returned for postoperative evaluation at 1 week, 2 weeks, and just prior to surgical uncovering. The surgical sites were assessed for pain, swelling, erythema, and purulence. Results: In the first group, 3 patients developed wound dehiscence at 5 implant sites and 1 developed a minor inflammatory response. None of the patients in this group received further antibiotics. In the second group, 3 patients developed wound dehiscence, 2 developed an inflammatory response, and 1 was diagnosed with infection, for which another course of antibiotics was required. There was no statistical difference between the 2 groups according to the Fisher 2 × 4 exact test (P = .56). Discussion: Indiscriminate use of antibiotics is unacceptable in clinical practice today. Surgeons must adhere to basic principles to gain the most benefit from the use of prophylactic antibiotics. Conclusion: Long-term prophylactic antibiotic use in implant surgery was of no advantage or benefit over a single-dose preoperative antibiotic regimen in this patient population.

Purpose: The aim of this study was to compare a new method for the production of platelet-rich plasma (PRP), the plasma-rich-in-growth-factors kit (PRGF kit; G.A.C. Medicale San Antonio, Vitoria, Spain), with an established method, the Platelet Concentrate Collection System (PCCS; 3i/Implant Innovations, Palm Beach Gardens, FL) with respect to resulting cellular and growth factor contents. Materials and Methods: Whole blood was drawn from 51 healthy donors (20 men, 31 women) aged 19 to 59 years (mean ± SD 35.12 ± 9.65 years), and PRP was prepared by both methods. Results: Platelet counts differed significantly (signed rank test, P .001 for all) between the donor blood (274,200 ± 54,050/µL), the PCCS PRP preparation (1,641,800 ± 426,820/µL), and the PRGF kit PRP preparation (513,630 ± 139,470/µL). The PCCS concentrated leukocytes (whole blood, 6,992 ± 2,011/µL; PCCS PRP, 14,153 ± 7,577/µL), while the PRGF kit produced a leukocyte-poor PRP (65 ± 108/µL). Higher concentrations of transforming growth factor ß1 (TGF-ß1) and platelet-derived growth factor AB (PDGF-AB) were found in the PCCS PRP (TGF-ß1, 290 ± 95 ng/mL; PDGF-AB, 157 ± 62 ng/mL) than in the Anitua PRGF kit PRP (TGF-ß1, 73 ± 26 ng/mL; PDGF-AB, 47 ± 21 ng/mL). Statistical analysis showed significant differences (P .001 for TGF-ß1 and P .01 for PDGF-AB). Discussion: The results of this study and some data in the literature indicate that the content of growth factors in PRP can vary tremendously, depending on the system used for the preparation of PRP. Conclusion: PCCS collects more platelets and leukocytes than the PRGF kit. This results in significantly higher growth factor levels. Further in vivo studies are needed to determine whether this results in a clinically different biologic effect.

Purpose: No consensus exists on the long-term performance of hydroxyapatite (HA) coatings on dental implants. The aim of this study was to evaluate the long-term stability of the HA coating in a human autopsy specimen. Materials and Methods: Two mandibular HA-coated implants were retrieved postmortem from a woman after 10 years of functional loading with an implant/tooth-supported fixed partial denture. After ground sectioning, the specimens were histomorphometrically analyzed. Results: Direct bone-implant contact was found at 78.48% of the implant surface. HA coating disappearance had occurred in a few areas (22.75%), but bone was in direct apposition to the titanium surface. Bone volume measured 27.66%, and expected bone-implant contact was 37.55%. No inflammatory reaction was seen in the supracrestal soft tissues or the bone compartment. Discussion: Most of the HA coating was maintained on the implants, and areas lacking HA were directly apposed by bone. This observation suggests that the underlying titanium surface should have a macro-texture to promote the adaptation of bone to the titanium surface in case of HA disappearance, as well as to decrease failure at the HA-titanium interface. Conclusions: In a patient in whom prosthetic treatment was appropriately performed and proper plaque control was maintained, the HA coating was not damaged and contributed to the success of the implant over 10 years of clinical functioning.

The aim of vertical augmentation of the alveolar ridge is to restore resorbed alveolar ridges. This techniqueis critical to the placement of dental implants in a favorable position and the enhancement ofrestoration esthetics. The present report describes a technique for surgical preservation of the anteriormaxillary process using maxillary bone from the surgical site and raising a soft tissue rotated palatalflap. Maxillary lateral incisor extraction and periapical surgery of the central incisors were first carried out. Two bone cores were harvested from the neighboring buccal vestibular region and placed in thesockets of the lateral maxillary incisors. After 3 months, implants were placed; 12 weeks later, theprosthetic restorations were cemented. There were no complications after 2 years of follow-up. Thistechnique constitutes a viable approach for preserving the anterior sector alveolar ridge with the posteriorplacement of dental implants.