The International Journal of Oral & Maxillofacial Implants, 06/2004

Purpose: Attachment of bacteria to titanium may differ not only between bacterial species but also between strains within a species. The aim of the present in vitro study was to examine differences in bacterial attachment using 4 gram-negative anaerobic species of bacteria that are considered potential periodontal pathogens. Materials and Methods: The attachment of clinical and laboratory strains (n = 23) representing 2 Fusobacterium nucleatum subspecies, Porphyromonas gingivalis, and Prevotella intermedia to smooth, commercially pure titanium was examined using scanning electron microscopy. Results: All bacterial strains were attached to the smooth titanium surface by their outer membrane. F nucleatum cells were poorly attached to the titanium, unlike P gingivalis or P intermedia cells, but only slight differences were observed in the quantity of attached cells between the strains within each bacterial group. Discussion: In favorable conditions, some anaerobes can attach directly to an inert titanium surface. Microbial adhesion and subsequent colonization on the dental implant surface can lead to infecttion of the peri-implant tissue. Conclusion: The results indicated that the avidity of bacterial attachment to a smooth titanium surface varies between species of oral gram-negative anaerobes but not between strains.

Purpose: The purpose of this study was to determine whether the passive fit of the implant-retained single-cast framework could be improved by spark erosion treatment. Materials and Methods: An initial cast was produced in a transparent resin material. Five Brånemark System implants were arranged in the interforaminal region, and abutments were placed on them with a torque of 20 Ncm. An impression was made using a standard impression technique described by Brånemark. A corresponding master cast suitable for the spark erosion post-framework fabrication was produced. From this master cast, 12 frameworks were produced in a conventional single-cast procedure. Six of these were made of a high-gold alloy (Stabilor G); the other 6 were made of pure titanium (Biotan). These frameworks were then refined using the SAE Secotec Spark Erosion System. To measure the accuracy of the framework fit, the frameworks were measured before and after the spark erosion treatment using 2 different measurement methods-scanning electron microscopy to measure the gap widths (Sheffield test) and photoelastic stress analysis. Results: The results of both measurement techniques correlated and demonstrated significant improvement in the accuracy of fit or in the passive fit for all 12 frameworks after spark erosion treatment. This improvement was statistically significant for the titanium frameworks. Discussion: Dental practitioners and technicians should strive to achieve a precise passive fit of frameworks and superstructures to minimize additional stress at the interfaces of the prosthesis, abutment, and implant. Conclusion: The clinical use of the spark erosion technique to refine framework fit is recommended. (More than 50 references.)

Purpose: This finite element analysis was conducted to determine the magnitude of stress in the supporting bone when implants were arranged in either a straight-line or an offset configuration. In addition, the effects of axial and nonaxial loading and changes in prosthesis height were assessed. Materials and Methods: An 8-node hexahedral solid-element 3-dimensional finite element analysis model of the mandible was created using PATRAN software. Three titanium endosseous implants were placed in the model 7 mm apart. The center implant was placed on the line from the centers of the terminal implants (no offset), 1.5 mm lateral to this line (1.5-mm offset), or 3.0 mm lateral to this line (3.0-mm offset). Forces of 200 N were applied to a point corresponding to the center of the middle implant when the implants were in a straight-line configuration. Forces were applied in a straight vertical direction or in 15-degree increments to the vertical to a maximum of 60 degrees. Simulated type IV gold prostheses were made to simulate heights of 6 and 12 mm. Results: The least stress in the supporting bone was found with vertical loading of the no-offset implants with the 6-mm prosthesis (3.12 MPa) followed by the same alignment with the 12-mm prosthesis (3.86 MPa). Changing the angle of force application by 15 degrees resulted in increased stress to the underlying bone, and the creation of an offset did not fully compensate for this increased stress. Discussion: In contrast to previous studies, this study examined 3 elements not previously studied together in a single finite element analysis, using the maximum offset defined by normal anatomic contours of mandibular premolar and molar teeth, thereby describing the relative importance of clinically relevant methods for stress reduction. Conclusions: Vertical loading of an implant-supported prosthesis produced the lowest stress to the supporting bone. Changes in the angle of force application resulted in greater stress to supporting bone. Reduction in prosthesis height or use of an offset implant location for the middle implant reduced stress, but the reduction did not compensate for the increase found with off-axis loading.

Purpose: Late failure, which occurs after successful osseointegration, is usually attributed to prosthodontic determinants. Corrosion of metallic suprastructures and incorrectly handled materials are often primary causes of late implant failure. In this study, 6 implants whose failure was related to suprastructure metal corrosion and adjacent bone were investigated. Materials and Methods: Six implants as well as their suprastructures were analyzed for surface corrosion using light and scanning microscopy. Metal alloys and soldering compounds were analyzed using energy-dispersive x-ray analysis. Bone adhering to the implants was removed and analyzed for metal content using atom absorption spectroscopy. Results: Extensive corrosion lesions and areas of oxidation were detected on all 6 of the implants and inner crown surfaces. Bone tissue collected from 5 of the implants showed higher contents of metal ions in comparison to physiologic baseline values detected in healthy bone. Discussion: In spite of the high gold content of the suprastructure, corrosion occurred. Bonding oxides necessary for the process of fusing porcelain to gold will initiate corrosion. Apparently, once corrosion is initiated it rapidly progresses at the gap crevices, and toxic metal ions are released. These toxic ions diffuse into the peri-implant bone, causing bone structure breakdown and hastening osseodisintegration. Conclusion: Biocompatible metals, alloys, and ceramics should be used for implant-supported suprastructures. It is also essential that gaps between the implant and its suprastructure be avoided by cementing the suprastructure or sealing the gap.

Purpose: The effects of 2 graft materials, ß-tricalcium phosphate (Cerasorb) alone and a combination of Cerasorb and platelet-rich plasma (PRP), on the bone regeneration process were evaluated in the canine mandible. Materials and Methods: The mandibular premolars of 12 beagle dogs were surgically removed. The extraction sockets were filled with Cerasorb on the control side and a mixture of Cerasorb and PRP on the test side. Bilateral biopsy samples were taken from the graft insertion sites at 6, 12, and 24 weeks after surgery. Sections were prepared from the undecalcified resin-embedded samples. Results: Six weeks after grafting, the proliferation of cellular osteogenic mesenchyma was more abundant in the test group. The histomorphometric data revealed a significantly higher percentage of bone area in the test group (45.9%) than in the control group (30.8%) (P < .05). Twelve weeks after grafting, the test group still had some advantage over the control group in terms of bone regeneration (52.5% bone in the test group versus 49.4% in the control group, P < .05). Twenty-four weeks after grafting, bone-forming activity was nearly equal in the 2 groups, and the bone area in the 2 groups did not differ significantly (62.9% and 61.9%, respectively) (P < .05). Discussion: The histomorphometric results suggested more intensive bone regeneration in the early healing phase following the topical application of PRP. Conclusion: The increase in bone density facilitated by grafting with a combination of Cerasorb and PRP requires thorough study in humans.

Purpose: Tissue reactions to 4 different implant surfaces were evaluated in regard to the development and progression of ligature-induced peri-implantitis. Materials and Methods: In 6 male mongrel dogs, a total of 36 dental implants with different surfaces (9 titanium plasma-sprayed, 9 hydroxyapatite-coated, 9 acid-etched, and 9 commercially pure titanium) were placed 3 months after mandibular premolar extraction. After 3 months with optimal plaque control, abutment connection was performed. Forty-five days later, cotton ligatures were placed around the implants to induce peri-implantitis. At baseline and 20, 40, and 60 days after placement, the presence of plaque, peri-implant mucosal redness, bleeding on probing, probing depth, clinical attachment loss, mobility, vertical bone loss, and horizontal bone loss were assessed. Results: The results did not show significant differences among the surfaces for any parameter during the study (P > .05). All surfaces were equally susceptible to ligature-induced peri-implantitis over time (P < .001). Correlation analysis revealed a statistically significant relationship between width of keratinized tissue and vertical bone loss (r² = 0.81; P = .014) and between mobility and vertical bone loss (r² = 0.66; P = .04), both for the titanium plasma-sprayed surface. Discussion and Conclusions: The present data suggest that all surfaces were equally susceptible to experimental peri-implantitis after a 60-day period.

Purpose: The purpose of this prospective clinical and radiographic study was to evaluate Biolok implants used for single-tooth replacement during 5 years of function. Materials and Methods: Thirty-nine patients received Biolok implants for single-tooth replacement. Clinical and radiographic recordings were made at baseline (placement of restoration) and at 1, 3, and 5 years. Plaque Index (PI), Gingival Index (GI), and clinical attachment level were the clinical parameters recorded. Clinical attachment level was measured using a customized probing template and a standard pressure electronic probe. Bone level changes were measured from standardized radiographs. Clinical attachment level and bone level were recorded to the nearest 0.1 mm. Correlations between clinical attachment level, bone level, PI, and GI were evaluated. Results: The cumulative survival rate was 97.4% (38 of 39 implants). The mean clinical attachment level change over 5 years was a loss of 0.17 ± 0.23 mm. Significant correlations between clinical attachment level change and PI were found at 3 and 5 years (P < .015). Significant correlations between clinical attachment level change and GI were not found (P > .05). Mean bone loss was 0.83 ± 0.03 mm from baseline to 1 year, 0.26 ± 0.03 mm from 1 year to 3 years, and 0.14 ± 0.04 mm from 3 to 5 years. Significant correlations between bone level changes and PI or GI were not found (P > .05). Discussion: Over a 5-year evaluation period, the bone levels and clinical attachment levels were stable. These results were consistent with other studies of single-tooth implants. Conclusions: After 5 years of function, the results suggest that Biolok implants can be successfully used for single-tooth replacement.

Purpose: The aim of this prospective clinical study was to evaluate the survival rates at 12 months of transmucosal implants placed in the posterior mandible and immediately restored with single crowns. Materials and Methods: Thirty ITI dental implants with sandblasted, acid-etched surfaces were placed in 30 patients missing at least 1 mandibular molar and immediately restored if acceptable primary stability was attained. Primary stability was measured with resonance frequency analysis (RFA) using the Osstell device, and only implants with a stability quotient greater than 62 were included in the study. RFA measurement and radiographic assessment were made at baseline and 6 months after implant placement. Plaque Index, Bleeding Index, probing depth, attachment level, and width of keratinized tissue were measured at the 12 month follow-up examination. Results: At 12 months, only 1 implant had been lost; it was removed because of acute infection. Radiographic as well as clinical examination confirmed osseointegration of all implants, with a survival rate of 96.7%. Discussion: Interestingly, implant stability as measured using RFA did not increase significantly from baseline to 12 months (P > .05). Conclusion: The present study showed that immediate restoration of transmucosal implants placed in the mandibular area with good primary stability can be a safe and successful procedure. However, larger, long-term clinical trials are needed to confirm the present results.

Purpose: To investigate peri-implant bone resorption around 108 ITI dental implants 1 year after prosthetic loading using extraoral panoramic, conventional intraoral periapical, and digital radiologic techniques. Materials and Methods: A total of 108 implants were placed (59 in the maxilla and 49 in the mandible) in 42 patients (16 men and 26 women) with a mean age of 44.2 years (range 14 to 68 years). Orthopantomographic, conventional periapical, and digital radiographs were obtained at loading and again 1 year later. Bone loss was calculated from the difference between the initial and final measurements. Results: Mean loss in alveolar bone height was determined to be 1.36 mm by extraoral panoramic radiography, 0.76 mm by intraoral periapical radiography, and 0.95 mm by digital radiography. The implants located in the maxilla and those placed in patients who smoked 11 to 20 cigarettes per day were associated with significantly greater bone loss. Discussion: The results in relation to peri-implant bone loss in the first year after loading were similar to those published by other authors. Conclusion: Conventional periapical films and digital radiographs were more accurate than orthopantomography in the assessment of peri-implant bone loss. Smoking and implant location in the maxilla were associated with increased peri-implant marginal bone resorption.

Purpose: In this study, preliminary results of immediate loading of ITI sandblasted, large-grit, acid-etched (SLA) implants with a bar-connected overdenture in the edentulous mandible are presented. Materials and Methods: Ten edentulous patients between 48 and 74 years old were included in this study. All patients received 2 SLA-surfaced ITI solid-screw dental implants in the interforaminal region, which were loaded with a bar connector and an overdenture 1 day after implant placement. Marginal bone resorption was evaluated using periapical radiographs. Gingival health (ie, Bleeding Index) and patient satisfaction (measured using a visual analog scale) were evaluated. Follow-up time was 24 to 36 months (mean time 29.8 months) after implant loading. Results: Twenty-four months after placement, none of the 20 implants had failed. Marginal bone resorption around all implants after 12 months averaged 0.71 mm, and 92% of the sites had a Bleeding Index of 0. Between 12 and 24 months, average bone resorption was an additional 0.08 mm. All patients demonstrated an improved quality of life. Discussion: The amount of bone resorption was comparable to amounts reported in studies with standard loading times. The low rate of inflammation of the peri-implant soft tissue and the high level of patient satisfaction in this study demonstrate encouraging short-term results. Conclusion: The results suggest that immediate loading of 2 dental implants can be successful and further support the use of a rough implant surface in residual bone.

Purpose: This study compares implant survival and patterns of implant failure in periodontally compromised and periodontally healthy patients. Materials and Methods: In a private periodontal practice, over a 13-year period, implants were placed in both periodontally compromised and periodontally healthy patients. Implants were classified in 5 different groups according to surface texture. Survival rates in each group were compared according to implant location, diameter, length, and phase of treatment. Results: A total of 1,511 implants were placed in 334 patients. One hundred fifty-one of these patients, classified as periodontally compromised patients (PCP), received 923 implants. The remaining 183 patients, classified as periodontally healthy patients (PHP), received 588 implants. The overall survival rate for implants placed in the PHP group was 93.7%, compared to 90.6% in the PCP group. The survival rate of hydroxyapatite-coated implants was 92.6% in the PHP group and 81% in the PCP group. The survival rate of the turned-surface implants was similar in both groups. Discussion: Two types of implant failure were identified. The first was failure of the implant to osseointegrate. This type of failure occurred early in treatment and appeared to be related to smooth-surface implants placed in bone of low density. Failures of this type were distributed equally between the PHP and PCP groups. The second type of failure was related to peri-implantitis. It was observed most often with implants with hydroxyapatite surfaces, occurred as the result of a progressive condition, and was most prevalent in the PCP group. Conclusion: Further long-term controlled investigations are needed to determine the influences of implant suface and host susceptibility on implant failure in both PHP and PCP.

Purpose: The aim of the present prospective study was to evaluate the concept of early loading of rough-surfaced implants in the completely edentulous maxilla and in the edentulous posterior mandible and maxilla. Materials and Methods: Fifty-four consecutive patients were treated. Twenty patients were completely edentulous in the maxilla (group A), 19 patients were edentulous in the posterior left and/or right maxilla (group B), and 15 patients were edentulous in the posterior left and/or right mandible (group C). One patient in group B and 5 in group C were bilaterally treated. Two hundred thirty-four solid screw-type, sandblasted, large-grit, acid-etched (SLA) ITI implants were placed, 58 (25%) immediately after tooth extraction. Mean placement torque and standard deviations were measured at all sites. Sixty fixed prostheses were delivered after a mean delay of 9 days (range, 4 to 22 days). Mean marginal bone reduction was measured after 1 year of loading. Results: Two implants were lost (0.9%), 1 before functional loading and 1 after 1 year. All other implants were clinically stable, with a mean marginal bone loss of 0.75 mm (± 1.3 mm). Marginal bone loss ranged from 0 to 3.5 mm. Mean placement torque on implants placed in healed bone or immediately after tooth extraction ranged from 29.1 ± 9.3 Ncm to 35.5 ± 5.8 Ncm. No statistical difference was found (P > .05) between implants placed in healed bone and those placed immediately after tooth extraction. Discussion: There is little documentation for immediate or early loading in the areas studied. However, in this study, favorable results were obtained in 54 consecutive patients in these regions. Conclusion: In this study population, early loading protocols can be applied with predictable results using rough-surfaced implants for rehabilitation of the completely edentulous maxilla, posterior maxilla, and posterior mandible.

Purpose: This retrospective study documents 5 years of clinical experience with Frialit-2 implants. Materials and Methods: A total of 1,215 implants (338 immediately placed, 877 placed according to a delayed-placement protocol) were placed in 487 patients. After exclusion criteria were applied, 1,099 implants (322 immediate, 777 delayed) in 442 patients remained. The influence of delayed versus immediate placement on the survival of these 1,099 implants was analyzed. The influence of diameter and location (maxilla versus mandible) on survival of the implant were also examined. Implantation sites included anterior and posterior regions; the surgical protocol (ie, immediate or delayed placement) was selected according to the indications for each site. Immediate implants were placed at the time of extraction, while delayed implants were placed 8 to 12 weeks postextraction. A 2-phase surgical protocol was used for all implants. Follow-up time ranged from 5.8 to 67.4 months. Results: According to the Kaplan-Meier method, the cumulative survival rate (CSR) was determined to be 90.05% at 5 years with 103 failures (32 immediate, for a CSR of 90.03%; 71 delayed, for a CSR of 90.04%). The lowest CSR (85%) was seen in the 3.4-mm-wide implants, while the 3.8-mm-wide implants had the highest CSR (93.16%). The CSR for implants in the maxilla was 91.08%; the CSR for implants in the mandible was 89.11%. Discussion: The CSR was relatively low compared to studies by other authors, who reported on implant populations much smaller than that presented here. Conclusions: A relatively low overall CSR was found, and more than 70% of the failures occurred prior to uncovering (loading) or within 2.5 months of uncovering in this patient population.

This article describes a method for harvesting intramembranous bone from the paranasal bone around the piriform aperture for lateral alveolar ridge augmentation and simultaneous implant placement in the anterior maxilla. In particular, the technique is recommended for situations where a maxillary incisal implant is being placed and ridge augmentation is needed to cover exposed threads. Surgical access is simple and can be accomplished by the same incision, and bone harvesting can be accomplished under local anesthesia. Postoperative morbidity is not yet known.

Hereditary ectodermal dysplasia is an inherited disorder characterized by aplasia or dysplasia of ectodermal tissues, such as hair, nails, teeth, and skin, that occurs in approximately 1 in every 100,000 live births. Dental abnormalities and abnormal facial appearance are of major concern in childhood and adolescence, since they can restrict the individual socially and affect his or her self-confidence. Oral rehabilitation in the early stages of the patient's life may provide functional and esthetic restoration as well as safeguard psychologic health. This report presents the clinical procedures involved in the rehabilitation of a 10-year-old female patient with complete bilateral cleft lip and palate and ectodermal dysplasia.

Implant placement to provide support and retention for nasal prostheses has been described in the literature. The anatomic sites that have been utilized for implant placement are the nasal bones, the premaxillary area through the nasal fossae, and the anterior wall of the frontal sinus. In the patient described, after a presurgical computerized tomography scan to determine adequacy of bone volume, 1 conventional threaded hydroxyapatite-coated root-form implant, created for intraoral use, was placed in the frontal process of the maxillary bone and 2 additional conventional implants were placed in the premaxillary area through the nasal fossa. Six months after implant placement, second-stage surgery was completed. A single bar connecting the 3 implants was fabricated. The removable nasal prosthesis was retained on the bar with 2 clips. An examination 1 year postsurgery revealed no clinical signs of pathosis. Long-term clinical follow-up of this case should continue and a sufficient number of additional cases should be investigated before use of the frontal process of the maxillary bone for implant retention can be recommended on a routine basis.

Purpose: The objective of this study was to report the clinical outcome of dental implants placed in revascularized fibula flaps for the reconstruction of severely atrophied edentulous maxillae and immediately loaded with full-arch implant-supported prostheses. Materials and Methods: Two patients, a 55-year-old woman and a 59-year-old woman, who presented with severely atrophied edentulous maxillae and local anatomy incompatible with rehabilitation with conventional complete removable dentures and insufficient bone volume for placement of implants of adequate dimensions were selected for reconstruction with revascularized fibula free flaps. Three months after the reconstructive procedure, Brånemark System dental implants (8 in the 55-year-old patient, 7 in the 59-year-old patient) were placed in the reconstructed areas and immediately loaded with implant-supported full-arch prostheses. The mean follow-up period of implants after the start of prosthetic loading was 24 months. Radiographic peri-implant bone level changes and peri-implant clinical parameters (Plaque Index, Bleeding Index, and probing depth) were evaluated. Results: No implants were lost during the follow-up period. Implant survival and success rates were 100% and 93.3%, respectively. Peri-implant clinical parameters presented values consistent with those obtained for implants placed in native nonreconstructed bone and allowed to heal before loading. Discussion: To the authors' knowledge, this is the first time that the successful immediate loading of implants placed in fibula free flaps for the rehabilitation of totally edentulous patients with severely resorbed maxillae or mandibles has been described. Conclusion: Despite the limited number of patients and the short follow-up period, immediate loading of implants placed in revascularized fibula free flaps appears to be a reliable method for the dental rehabilitation of these patients.