Digitizing implant position locators on master casts: comparison of a noncontact scanner and a contact-probe scanner.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):29-35
Authors: Holst S, Persson A, Wichmann M, Karl M
Abstract
Purpose: Although several investigations of the fit of computer-aided design/computer-assisted manufactured implant restorations have been reported in the literature, very limited information is available on the accuracy of dental scanners for surface data acquisition. The objective of this research project was to investigate the accuracy and repeatability of a three-dimensional noncontact laser scanning system based on conoscopic holography recording the spatial orientation of an implant in vitro. Materials and Methods: One master cast containing five nonparallel implant replicas with scan abutments (implant position locator [IPL], Nobel Biocare) was repeatedly digitized by two commercially available dental scanners and an industrial highprecision coordinate measuring machine as a reference. Repeated measurements of the center point and vector analysis were applied to determine the accuracy and repeatability of IPL orientation. The Wilcoxon signed rank test modified for equivalence was applied to determine whether the systems were equally accurate based on given threshold limits of 0.010, 0.005, and 0.001 mm. Results: All between-system tests identified significant differences, although most differences were very small in absolute terms. Tests for equivalence based on difference windows were exploratorily significant for 0.010 and 0.005 mm. Conclusion: Conoscopic holography scan technology is a valid option to supplement dental touch-probe scanners for laboratory digitization of implant master casts.
Influence of abutment height and surface roughness on in vitro retention of three luting agents.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):36-41
Authors: Cano-Batalla J, Soliva-Garriga J, Campillo-Funollet M, Munoz-Viveros CA, Giner-Tarrida L
Abstract
Purpose: This study evaluated the effects of abutment height, airborne-particle abrasion, and type of cement on the tensile resistance to dislodgement of cement-retained implant restorations. Materials and Methods: Three groups of 12 standardized abutments each were prepared with different heights (4 mm, 5 mm, and 6 mm) using a milling machine. Crowns were cast in cobalt-chrome using the lost-wax technique, airborne particle-abraded using 50-Μm aluminum oxide, and cleaned with acetone. Restorations were cemented using a noneugenol acrylic urethane cement, a resin-modified glass ionomer, or a zinc oxide-noneugenol cement. A 5-kg load was applied for 10 minutes. Samples were kept at 37°C and 100% humidity overnight. A tensile force was applied to the crown using a testing machine at a crosshead speed of 5 mm/minute until failure occurred. Next, the abutments were airborne particle-abraded with 50-Μm aluminum oxide, and the cementation and testing procedures were repeated. The effects of cement, abutment height, and surface treatment were evaluated statistically. Results: There were significant differences among the cements. The resin-modified glass ionomer provided the greatest retention in all the tested conditions, while the zinc oxide-noneugenol cement produced the lowest retention values. Significant differences were also detected between 4-mm and 6-mm abutments, with the 6-mm abutments being more retentive. No differences were found between 4-mm and 5-mm abutments or between 5-mm and 6-mm abutments. The effect of airborne-particle abrasion was also found to be significant. A maximum increase of 90 N in retention force was observed after airborne-particle abrasion for the 5-mm abutments cemented with the acrylic urethane cement. Conclusions: Cement, airborne-particle abrasion, and abutment height can significantly influence retention of implant-supported crowns. Different parameters, including those specific to the patient, should be considered in the selection of a luting agent.
Screw loosening with interchangeable abutments in internally connected implants after cyclic loading.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):42-7
Authors: Kim SK, Koak JY, Heo SJ, Taylor TD, Ryoo S, Lee SY
Abstract
Purpose: The purpose of this study was to observe and compare any loosening of screws attaching several interchangeable abutments to internally connected implants after cyclic loading. Materials and Methods: Four different abutment groups mated with Straumann single-stage transmucosal implants (n = 7 each group) were assessed: Straumann solid abutment, Restore COC abutment, Neoplant solid abutment, and AVANA solid abutment. Each implant was fixed rigidly in a special holding jig. Abutments were tightened to 35 Ncm with a torque controller. A cyclic load of 150 N at a 30-degree angle to the long axis was applied to the implants for 1 million cycles. Prior to loading, Periotest values (PTVs) were measured. After cyclic loading, PTVs were measured and removal torque values (RTVs) of abutments were measured with a digital torque gauge. Results: No mechanical failures were noted for the Straumann solid abutment or the Restore COC abutment. Six Neoplant abutment screws fractured (86%), and four implants fractured (57%) in the group restored with AVANA solid abutments. The RTVs of the Straumann solid abutment were significantly higher than those of the other abutments. The final mean PTV of the Straumann solid abutment was significantly lower than the final mean PTVs of the other abutments. The final mean PTV (4.76 ± 5.58) was significantly higher than the initial mean PTV (-4.29 ± 0.47). Conclusions: Although different abutments are interchangeable with each other, they possess different chemical compositions and physical characteristics. The use of an abutment and implant manufactured by the same company is recommended to prevent the loosening of the abutment screw.
Relationship between subsinus bone height and bone volume requirements for dental implants: a human radiographic study.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):48-54
Authors: Kopecka D, Simunek A, Brazda T, Rota M, Slezak R, Capek L
Abstract
Purpose: To analyze the vertical dimension of subsinus alveolar bone that is available for placement of endosseous implants. Materials and Methods: Subsinus alveolar bone height (SBH) was determined via radiographs and categorized into three groups: Group A corresponded to SBH < 5 mm; group B SBH of 5 to 9 mm; and group C, SBH > 9 mm. Statistical analysis was carried out using the Wilcoxon paired test with the threshold for statistical significance set at P < .05. Results: Five hundred eighty-three panoramic radiographs of edentulous maxillae were analyzed. In 96.9% of radiographs, the anterior border of the maxillary sinus was above the first premolar. Mean SBH values for canine, first premolar, second premolar, first molar, and second molar sites were 11.4 ± 6.2 mm, 10.6 ± 3.8 mm, 5.9 ± 2.5 mm, 3.3 ± 2.2 mm, and 4.5 ± 2.4 mm, respectively. Representations of groups A, B, and C in the canine region were 14.3%, 21.4%, and 64.3%, respectively; in the first premolar region they were 8.3%, 22.3%, and 69.4%, respectively; in the second premolar region, these were 31.6%, 60.9%, and 7.5%, respectively; in first molar region, the values were 73.1%, 25.4%, and 1.5%, respectively; and in the second molar region they were 54.2%, 41.7%, and 4.1%, respectively. Conclusions: The mean SBH is the highest in the area of the anterior border of the sinus; it declines significantly toward the posterior maxilla, reaches its minimum in the area of the first molar, and increases again significantly in the second molar region. From a clinical point of view, the lateral window technique of sinus elevation remains the dominant augmentative procedure in the molar area, whereas in the premolar area, less invasive alternative methods may be more appropriate.
The effect of changes in head position on enlargement of structures during panoramic radiography.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):55-63
Authors: Pfeiffer P, Bewersdorf S, Schmage P
Abstract
Purpose: Accuracy of panoramic radiographs is essential for distance measurements during implant planning, but it might be compromised by various factors. The aim of the present study was to evaluate the effect of vertical and horizontal head positioning on area-dependent enlargement ratios of digital panoramic radiography. Materials and Methods: The mandible of a dry skull was marked with small steel globes. The skull was moved 1 to 4 degrees in 1-degree increments to the left and right and up and down. A series of 17 panoramic radiographs was obtained with the same digital radiographic device. For the rotated skull, horizontal and vertical distances, indicated by the steel globes, were compared to the distances with the ideal positioning of the skull. The results were analyzed statistically. Results: Head positioning and angulation, anatomical site, and distance orientation influenced horizontal measurements. Enlargement ratios of horizontal distances of the right canine and first molar regions (skull rotation to the right 2 to 4 degrees) were significantly lower than those for the corresponding anatomical sites on the left side. Horizontal distance measurements of the different anatomical sites of the left and the right jaw did not differ significantly from each other when the skull was moved downward. When the skull was rotated upward, no significant differences were obtained for corresponding anatomical sites of the right and left arches. Enlargement ratios of vertical distances of different anatomical sites, as well as within the same anatomical site, were not significantly different from each other for the given skull rotations. Conclusions: Ideal head positioning for digital panoramic radiographs is mandatory to avoid improper enlargement ratios of horizontal distances, which can be important in implant dentistry.
Effect of oral bacteria on the mechanical behavior of titanium dental implants.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):64-8
Authors: Gil FJ, Rodriguez A, Espinar E, Llamas JM, Padulles E, Juarez A
Abstract
Purpose: This study sought to determine whether the mechanical properties of titanium dental implants changed after exposure to bacteria. Materials and Methods: Two strains of bacteria (Streptococcus sanguinis and Lactobacillus salivarius) were used in the study. The adhesive properties of the two strains were investigated as follows. Titanium implants were placed in bacteria broth, seeded with the two bacteria strains, and left in the broth for 1 or 3 months. Another group of titanium implants was immersed in artificial saliva at 37°C for 3 months. Ten implants in each group were tested in 37°C artificial saliva to evaluate their mechanical flexural strength and fatigue life. Results: The bacterial cultures grew quickly on titanium surfaces. After 1 month of bacteria culture in vitro, the bacteria had produced corrosion pits on the titanium surfaces. After 3 months of bacterial culture, a 7% decrease in the flexural strength of the implant samples and a decrease of 15% in the number of cycles to failure by fatigue were seen versus implants not exposed to bacteria. Conclusions: These results demonstrate that, in physiologic conditions in vitro, bacteria have the capacity to produce a pitting corrosion phenomenon on exposed titanium surfaces, leading to a significant deterioration in the mechanical properties of the implant. It is therefore logical to conclude that bacteria may produce corrosion that reduces the useful life of dental implants.
Trends in funding, internationalization, and types of study for original articles published in five implant-related journals between 2005 and 2009.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):69-76
Authors: Barao VA, Shyamsunder N, Yuan JC, Knoernschild KL, Assuncao WG, Sukotjo C
Abstract
Purpose: The aims of this study were to evaluate the trends in funding, geographic origin, and study types of original articles in the dental implant literature and to investigate the relationships among these factors. Materials and Methods: Articles published in Clinical Oral Implants Research, The International Journal of Oral and Maxillofacial Implants, Clinical Implant Dentistry and Related Research, Implant Dentistry, and Journal of Oral Implantology from 2005 to 2009 were reviewed. Nonoriginal articles were excluded. For each article included, extramural funding source, geographic origin, and study type were recorded. Descriptive and analytic analyses (α = .05), including a logistic regression analysis, and chi-square test were used where appropriate. Results: Of a total of 2,085 articles published, 1,503 met the inclusion criteria. The most common source of funding was from industry (32.4%). The proportion of studies that reported funding increased significantly over time. Europe represented the highest percentage (55.8%) of published articles. Most of the articles reported on clinical studies (49.9%), followed by animal studies (25.9%). Articles from Asia and South America and animal and in vitro studies were significantly more likely to be funded. Conclusion: Almost half of the original dental implant articles were funded. The trend toward internationalization of authorship was evident. A strong association was observed between funding and geographic origin and between funding and study type. Most studies in North America and Europe were clinical studies and supported by industry, whereas a greater proportion of studies in Asia and South America were in vitro or animal studies funded through government resources.
Effect of implant surface properties on peri-implant bone healing: implant stability and microcomputed tomographic analysis.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):77-83
Authors: Al-Hamdan SH, Junker R, Jansen JA
Abstract
Purpose: The present study aimed to evaluate and compare two types of implants: grit-blasted and acidetched implants (SLActive) and nanometer-scale hydroxyapatite-modified implants (NanoTite). Materials and Methods: Twenty-two SLActive and 22 NanoTite implants were inserted into the mandibles of 11 beagle dogs. The animals were divided into three groups according to healing time (group A, 2 weeks; group B, 4 weeks; group C, 8 weeks). Resonance frequency analysis (RFA) was performed immediately after implant placement and after 2, 4, and 8 weeks of healing. Two, 4, and 8 weeks after implantation, the animals were sacrificed and the amount of bone surrounding the implants was assessed using microcomputed tomography. Results: For SLActive and NanoTite implants, the RFA values decreased after 2 weeks and increased after 4 and 8 weeks of healing. After 8 weeks, the mean RFA value for SLActive implants was significantly higher than the mean RFA value for NanoTite implants. For the different healing periods, no significant differences in bone volume were seen for SLActive and NanoTite implants. Conclusions: SLActive and NanoTite implants evoked a similar bone response after implantation for 2, 4, and 8 weeks in a nonsubmerged position in the mandibles of dogs. In addition, the data confirmed that RFA is a reliable and noninvasive method to determine dental implant stability and the bone formation process at the clinical level.
Histomorphometric analysis following augmentation of the anterior atrophic maxilla with cancellous bone block allograft.
Int J Oral Maxillofac Implants. 2012 Jan;27(1):84-9
Authors: Nissan J, Marilena V, Gross O, Mardinger O, Chaushu G
Abstract
Purpose: Grafting with bone blocks may be required to restore the alveolar process in extremely atrophic maxillae prior to implant placement to ensure both function and esthetics. The present study was conducted to histologically and histomorphometrically evaluate the application of allograft cancellous bone blocks for the augmentation of the anterior atrophic maxilla. Materials and Methods: Consecutive patients with severe atrophy in the anterior maxilla underwent augmentation with cancellous bone block allografts. Bony deficiencies of at least 3 mm horizontally and up to 3 mm vertically according to computed tomographic para-axial reconstructions served as inclusion criteria. After 6 months, implants were placed and a cylindric sample core from the graft area was collected. All specimens were prepared for histologic and histomorphometric examination. Results: Forty patients were included in the study. Eighty-three implants were placed in bone that was augmented with 60 cancellous freeze-dried bone block allografts. The implant survival rate was 98.8%. Mean follow-up was 48 ± 22 months (range, 14 to 82 months). The mean percentage of newly formed bone was 33% ± 18%, that of the residual cancellous block allograft was 26% ± 17%, and marrow and connective tissue comprised 41% ± 2%. Statistically significant histomorphometric differences regarding newly formed bone and residual cancellous block allograft were found between younger (< 40 years) and older (≥ 40 years) patients, respectively. Age did not appear to influence the percentage of marrow and connective tissue. Conclusions: Cancellous bone block allograft is biocompatible and osteoconductive, permitting new bone formation following augmentation of extremely atrophic anterior maxillae in a two-stage implant placement procedure. New bone formation was age-dependent.
PMID: 22299083 [PubMed - in process]
PubMed requires this notice of disclaimer is present.
