Dental and Oral
Al Nawas, B., K.A. Groetz, H. Goetz, H. Duschner, and W. Wagner (2008). Comparative histomorphometry and resonance frequency analysis of implants with moderately rough surfaces in a loaded animal model. Clinical Oral Implants Research 19(1): 1-8. ISSN: 0905-7161.
Abstract: OBJECTIVES: Test of favourable conditions for osseointegration with respect to optimum bone-implant contact (BIC) in a loaded animal model. The varied parameters were surface roughness and surface topography of commercially available dental implants. METHOD: Thirty-two implants of six types of macro and microstructure were included in the study (total 196). The different types were: minimally rough control: Branemark machined Mk III; oxidized surface: TiUnite MkIII and MkIV; ZL Ticer; blasted and etched surface: Straumann SLA; rough control: titanium plasma sprayed (TPS). Sixteen beagle dogs were implanted with the whole set of the above implants. After a healing period of 8 weeks, implants were loaded for 3 months. For the evaluation of the BIC areas, adequately sectioned biopsies were visualized by subsurface scans with confocal laser scanning microscopy (CLSM). RESULTS: The primary statistical analysis testing BIC of the moderately rough implants (mean 56.1+/-13.0%) vs. the minimally rough and the rough controls (mean 53.9+/-11.2%) does not reveal a significant difference (P=0.57). Mean values of 50-70% BIC were found for all implant types. Moderately rough oxidized implants show a median BIC, which is 8% higher than their minimally rough turned counterpart. The intraindividual difference between the TPS and the blasted and etched counterparts revealed no significant difference. The turned and the oxidized implants show median values of the resonance frequency [implant stability quotients (ISQ)] over 60; the nonself-tapping blasted and etched and TPS implants show median values below 60. DISCUSSION: In conclusion, the benefit of rough surfaces relative to minimally rough ones in this loaded animal model was confirmed histologically. The comparison of different surface treatment modalities revealed no significant differences between the modern moderately rough surfaces. Resonance frequency analysis seems to be influenced in a major part by the transducer used, thus prohibiting the comparison of different implant systems.
Descriptors: dental implants, dental prosthesis design, osseointegration, endosseous, dental restoration failure, dogs, experimental, microscopy, confocal, models, animal, statistics, nonparametric, surface properties, vibration.
Alexander, H., J.L. Ricci, and G.J. Hrico (2009). Mechanical basis for bone retention around dental implants. Journal of Biomedical Materials Research. Part B, Applied Biomaterials 88(2): 306-11.
Abstract: This study, analytically, through finite element analysis, predicts the minimization of crestal bone stress resulting from implant collar surface treatment. A tapered dental implant design with (LL) and without (control, C) laser microgrooving surface treatment are evaluated. The LL implant has the same tapered body design and thread surface treatment as the C implant, but has a 2-mm wide collar that has been laser micromachined with 8 and 12 microm grooves in the lower 1.5 mm to enhance tissue attachment. In vivo animal and human studies previously demonstrated decreased crestal bone loss with the LL implant. Axial and side loading with two different collar/bone interfaces (nonbonded and bonded, to simulate the C and LL surfaces, respectively) are considered. For 80 N side load, the maximum crestal bone distortional stress around C is 91.9 MPa, while the maximum crestal bone stress around LL, 22.6 MPa, is significantly lower. Finite element analysis suggests that stress overload may be responsible for the loss of crestal bone. Attaching bone to the collar with LL is predicted to diminish this effect, benefiting crestal bone retention. Copyright 2007 Wiley Periodicals, Inc.
Descriptors: bone and bones cytology, dental implants, biomechanics, dogs, imaging, three dimensional, models, animal, wound healing.
Araujo, M., E. Linder, J. Wennstrom, and J. Lindhe (2008). The influence of Bio-Oss Collagen on healing of an extraction socket: an experimental study in the dog. International Journal of Periodontics and Restorative Dentistry 28(2): 123-35. ISSN: 0198-7569.
Abstract: The objective of the present experiment was to evaluate the effect on hard tissue modeling and remodeling of the placement of a xenograft in fresh extraction sockets in dogs. Five mongrel dogs were used. Two mandibular premolars (4P4) were hemisected in each dog, and the distal roots were carefully removed. In one socket, a graft consisting of Bio-Oss Collagen (Geistlich) was placed, whereas the contralateral site was left without grafting. After 3 months of healing, the dogs were euthanized and biopsies sampled. From each experimental site, four ground sections (two from the mesial root and two from the healed socket) were prepared, stained, and examined under the microscope. The presence of Bio-Oss Collagen failed to inhibit the processes of modeling and remodeling that took place in the socket walls following tooth extraction. However, it apparently promoted de novo hard tissue formation, particularly in the cortical region of the extraction site. Thus, the dimension of the hard tissue was maintained and the profile of the ridge was better preserved. The placement of a biomaterial in an extraction socket may promote bone modeling and compensate, at least temporarily, for marginal ridge contraction.
Descriptors: bone substitutes therapeutic use, collagen therapeutic use, minerals therapeutic use, tooth socket surgery, alveolar process pathology, alveolar process surgery, bicuspid surgery, biopsy, bone remodeling drug effects, connective tissue pathology, dogs, epithelial attachment pathology, mandible pathology, mandible surgery, models, animal, osteogenesis drug effects, periodontium pathology, surgical flaps, time factors, tooth extraction, tooth socket pathology, transplantation, heterologous, wound healing drug effects.
Artzi, Z., N. Givol, M.D. Rohrer, C.E. Nemcovsky, H.S. Prasad, and H. Tal (2003). Qualitative and quantitative expression of bovine bone mineral in experimental bone defects. Part 1: description of a dog model and histological observations. Journal of Periodontology 74(8): 1143-1152. ISSN: 0022-3492.
Abstract: Background: The purpose of this study was to evaluate histologically the contribution of inorganic bovine bone biomaterial in a new experimental bone defect in dogs at different healing periods and to examine newly formed bone around the grafted mineral particles and their relationship in membrane-protected (test) and non-protected intrabony (control) defects. Methods: Four round intrabony defects, 5X4 mm were made bilaterally (at different times) on the lateral bony mandibular angle in eight dogs. Two defects were filled with bovine bone mineral (BBM) particles and two remained non-grafted but were blood clotted. A collagen membrane covered each defect type (n=4). This procedure was repeated on the contralateral side at a different given time to obtain two different healing periods in each dog. Thus, four specimens were obtained at 3, 6, 12, and 24 months postoperatively for each healing period. The non-decalcification method (Donath technique) with Stevenel's blue and van Gieson's picro fuchsin staining was used for histological examination. Results: Newly formed bone was observed at all examined defect types. The BBM particles were clearly evident regardless of the healing period. At 3 and 6 months, newly formed bone, woven in nature, was incorporated with the grafted particles. High cellular bone with occasional osteoclasts was noted towards the surface of the mineral particles. No substantial difference was observed between the protected and the non-protected defects except for higher ossified centers around the membrane-protected defects. At the non-grafted sites, the membrane-protected defect showed newly formed bone near the bony walls, and particularly under the membrane, establishing a bony bridge over the defect at the healing periods. The non-grafted unprotected defect (control) showed bone formation only at the base and close to the bony walls leaving a healed concave configuration. At 1 and 2 years, the grafted sites showed full bone healing configuration. However, the grafted particles still dominated the previous defect area and were completely surrounded by the newly formed bone. Osteons and lamellar bone arrangement were established but the bone was still highly cellular and osteoclasts could still be identified. The non-grafted membrane-protected sites showed excellent bone healing although areas of non-mineralized soft tissue were often seen. The control sites healed but still presented with a concave surface configuration. Conclusions: BBM biomaterial is a highly osteoconductive material. In a 4-wall bony defect, newly formed bone was well evident in establishing excellent bone healing configuration with or without a regenerative biological barrier. The grafted material dominated the experimental sites with no substantial resorption at any healing period up to 2 years observation.
Descriptors: biomaterials, dental and oral system, ingestion and assimilation, skeletal system, movement and support, donath non decalcification method, laboratory techniques, stevenel's blue staining, histology and cytology techniques, collagen membrane, laboratory equipment, histology, histology and cytology techniques, inorganic bovine bone biomaterial, medical equipment, van gieson's picro fuchsin staining, bone formation, bony walls, concave surface configuration, grafted mineral particles, healing configuration, healing period, intrabony defect, membrane protected, non protected, ossified centers, osteoconduction.
Berglundh, T., I. Abrahamsson, M. Welander, N.P. Lang, and J. Lindhe (2007). Morphogenesis of the peri-implant mucosa: an experimental study in dogs. Clinical Oral Implants Research 18(1): 1-8. ISSN: 0905-7161.
Abstract: PURPOSE: The objective of the present experiment was to study the morphogenesis of the mucosal attachment to implants made of c.p. titanium. MATERIAL AND METHODS: All mandibular premolars were extracted in 20 Labrador dogs. After a healing period of 3 months, four implants (ITI Dental Implant System) were placed in the right and left sides of the mandible. A non-submerged implant installation technique was used and the mucosal tissues were secured to the conical marginal portion of the implants with interrupted sutures. The sutures were removed after 2 weeks and a plaque control program including daily cleaning of the remaining teeth and the implants was initiated. The animals were sacrificed and biopsies were obtained at various intervals to provide healing periods extending from Day 0 (2 h) to 12 weeks. The mandibles were removed and placed in the fixative. The implant sites were dissected using a diamond saw and processed for histological analysis. RESULTS: Large numbers of neutrophils infiltrated and degraded the coagulum that occupied the compartment between the mucosa and the implant during the initial phase of healing. At 2 weeks after surgery, fibroblasts were the dominating cell population in the connective tissue interface but at 4 weeks the density of fibroblasts had decreased. Furthermore, the first signs of epithelial proliferation were observed in specimens representing 1-2 weeks of healing and a mature barrier epithelium occurred after 6-8 weeks of healing. The collagen fibers of the mucosa were organized after 4-6 weeks of healing. CONCLUSION: It is suggested that the soft-tissue attachment to implants placed using a non-submerged installation procedure is properly established after several weeks following surgery.
Descriptors: dental implants, morphogenesis physiology, periodontium growth and development, blood coagulation physiology, collagen, connective tissue growth and development, connective tissue pathology, dental materials, dogs, epithelial attachment growth and development, epithelial attachment pathology, epithelium growth and development, epithelium pathology, fibroblasts pathology, fibroblasts physiology, mandible surgery, models, animal, neutrophils pathology, neutrophils physiology, periodontium pathology, titanium, wound healing physiology.
Bernard, J.P., S. Szmukler Moncler, S. Pessotto, L. Vazquez, and U.C. Belser (2003). The anchorage of Branemark and ITI implants of different lengths. I. An experimental study in the canine mandible. Clinical Oral Implants Research. 14(5): 593-600. ISSN: 0905-7161.
Abstract: The anchorage of machined Branemark and ITI TPS-coated implants of various lengths was investigated in an animal model. Branemark fixtures 7 and 10 mm long and ITI implants 6 and 10 mm long were inserted in the mandible of dogs and were reverse-torqued after 3 months of healing. The failing mode was different for the two implant systems. For the ITI implants, loosening coincided with the peak reverse-torque values. For the Branemark fixtures, two reverse-torque values were identified and recorded, a 'start to rotate' and a peak value. The 'start to rotate' values for the 7 and 10 mm Branemark fixtures were 36.67 and 38.57 Ncm, respectively, the peak values were 61.88 and 69.13 Ncm. The increase in implant length from 7 to 10 mm did not significantly improve the anchorage. The mean reverse-torque values for the 6- and 10-mm ITI implants were 104.66 and 192.25 Ncm, respectively; the difference was statistically significant. The mean removal torque of the 6-mm ITI implant was higher than the 7- and 10-mm Branemark implants. It is suggested that the distinct anchorage magnitude and the distinct loosening patterns registered for both implant systems might be related to the various surface states. The latter might account for the different failure tendencies mentioned in the literature for short Branemark and ITI implants.
Descriptors: animal model, testing, oral implants, torque, failure tendencies, Branemark and ITI implants.
Brink, J., S.J. Meraw, and D.P. Sarment (2007). Influence of implant diameter on surrounding bone. Clinical Oral Implants Research 18(5): 563-8. ISSN: 0905-7161.
Abstract: OBJECTIVES: Implant osseointegration is dependent upon various factors, such as bone quality and type of implant surface. It is also subject to adaptation in response to changes in bone metabolism or transmission of masticatory forces. Understanding of long-term physiologic adjustment is critical to prevention of potential loss of osseointegration, especially because excessive occlusal forces lead to failure. To address this issue, wide-diameter implants were introduced in part with the hope that greater total implant surface would offer mechanical resistance. Yet, there is little evidence that variation in diameter translates into a different bone response in the implant vicinity. Therefore, this study aimed at comparing the impact of implant diameter on surrounding bone. MATERIAL AND METHODS: Twenty standard (3.75 mm) and 20 wide (5 mm) implants were placed using an animal model. Histomorphometry was performed to establish initial bone density (IBD), bone to implant contact (BIC) and adjacent bone density (ABD). RESULTS: BIC was 71% and 73%, whereas ABD was 65% and 52%, for standard and wide implants, respectively. These differences were not statistically different (P>0.05). Correlation with IBD was then investigated. BIC was not correlated with IBD. ABD was not correlated to IBD for standard implants (r2=0.126), but it was correlated with wide implants (r2=0.82). In addition, a 1 : 1 ratio between IBD and ABD was found for wide implants. It can be concluded, within the limits of this study, that ABD may be influenced by implant diameter, perhaps due to differences in force dissipation.
Descriptors: dental implants, dental prosthesis design, mandible physiology, maxilla physiology, osseointegration physiology, biomechanics, bone density physiology, dogs, mandible anatomy and histology, maxilla anatomy and histology, models, animal, prospective studies, random allocation, stress, mechanical, surface properties.
Byun, J.H., B.W. Park, J.R. Kim, and J.H. Lee (2007). Expression of vascular endothelial growth factor and its receptors after mandibular distraction osteogenesis. International Journal of Oral and Maxillofacial Surgery 36(4): 338-44. ISSN: 0901-5027.
Abstract: During distraction osteogenesis, angiogenic activity is essential for new bone formation. This study examined the expression of vascular endothelial growth factor (VEGF) and two of its receptors, Flt-1 (VEGFR-1) and Flk-1 (VEGFR-2), in cellular components after mandibular distraction osteogenesis. Unilateral mandibular distraction (0.5 mm twice per day for 10 days) was performed in six mongrel dogs. Two animals each were killed on days 7, 14 and 28 after completion of distraction. The distracted mandibular segments and contralateral undistracted control segments were harvested and processed for immunohistochemical examination. Seven days after distraction, there was a significant increase in the expression levels of VEGF and its receptors in the osteoblasts, osteocytes and immature fibroblast-like cells compared to control specimens. These levels were maintained for 14 days after distraction in the osteoblasts and fibroblast-like cells. Twenty-eight days after distraction, VEGF and VEGFR-1 were expressed only moderately/weakly in the osteoblasts, and no VEGFR-2 expression was detected in the cellular component of the distracted bone. Throughout the observation period, VEGFR-1 expression was stronger than that of VEGFR-2. The expression patterns of VEGF and its receptors suggest that it plays an important role in osteogenesis, and that osteoblasts and immature fibroblast-like cells of the distracted bone may have an autocrine growth effect during distraction osteogenesis.
Descriptors: mandible surgery, osteogenesis, distraction, vascular endothelial growth factor a analysis, vascular endothelial growth factor receptor 1 analysis, vascular endothelial growth factor receptor 2 analysis, autocrine communication physiology, coloring agents diagnostic use, dogs, fibroblasts metabolism, immunohistochemistry, mandible cytology, mandible metabolism, models, animal, neovascularization, physiologic physiology, osteoblasts metabolism, osteocytes metabolism, osteogenesis physiology, time factors.
Choi, B.H., J. Li, H.S. Kim, C.Y. Ko, S.M. Jeong, and F. Xuan (2008). Comparison of submerged and nonsubmerged implants placed without flap reflection in the canine mandible. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics 105(5): 561-5.
Abstract: OBJECTIVE: The purpose of this study was to compare the bone healing around submerged and nonsubmerged implants installed in a canine mandible model using a flapless technique. STUDY DESIGN: Bilateral, edentulated, flat alveolar ridges were created in the mandibles of 6 mongrel dogs. After 3 months of healing, 2 implants were placed in 1 side by either miniflap submerged or flapless nonsubmerged procedures. After healing for an additional 8 weeks, microcomputerized tomography at the implantation site was performed. Osseointegration was calculated as the percent of the implant surface in contact with bone. Bone height was measured in the peri-implant bone. RESULTS: The mean osseointegration was greater (64.7%) in miniflap submerged sites than in the flapless nonsubmerged sites (56.8%; P < .05). The mean peri-implant bone height was greater (11.0 mm) in the miniflap submerged sites than in the flapless nonsubmerged sites (10.1 mm; P < .05). CONCLUSION: This study demonstrated that the submerged procedure was more effective than the nonsubmerged procedure in improving implant anchorage in the early phase after implant placement.
Descriptors: dental implantation, endosseous methods, dental implants, osseointegration, dental abutments, dental stress analysis, dogs, implants, experimental, mandible surgery, models, animal, random allocation, surgical flaps, tomography, x ray computed, wound healing.
Chung, S.H., S.J. Heo, J.Y. Koak, S.K. Kim, J.B. Lee, J.S. Han, C.H. Han, I.C. Rhyu, and S.J. Lee (2008). Effects of implant geometry and surface treatment on osseointegration after functional loading: a dog study. Journal of Oral Rehabilitation 35(3): 229-36.
Abstract: The purpose of this study was to evaluate the geometry and surface characteristics of osseointegration after functional loading by radiographic, periodontal and histomorphometric analyses. We analysed three groups of implants with different geometry and surface characteristics using experimental dogs. The control group received Branemark implants (group 1). Group 2 and group 3 implants each had a 0.5-mm pitch height but differed in surface characteristics. Group 2 implants were machine surfaced and group 3 implants were thermally oxidized at 800 degrees C for 2 h in a pure oxygen atmosphere. For these experiments, which used a total of four healthy beagle dogs, the implants were randomly installed into the extracted first, second and third premolar positions. The animals received radiographic and clinical periodontal examinations at 6 and 12 months post-loading, and were then killed for histomorphometric analysis. The radiographic analysis showed that mean crestal bone resorption in the control group was greater than that observed in the experimental groups (P < 0.05). The percentage of bone-to-implant contact for group 3 (83.7%) was significantly higher than in groups 1 (74.4%) and 2 (75.0%) (P < 0.05). Overall, implant geometry and surface treatment affected the rate of crestal bone resorption and bone healing surrounding the dental implants.
Descriptors: dental implantation, endosseous, dental implants, dental prosthesis design, osseointegration, bone remodeling, dental plaque index, dental stress analysis, dogs, models, animal, periodontal index, titanium, tooth socket pathology, treatment outcome.
Coelho, P.G., G. Cardaropoli, M. Suzuki, and J.E. Lemons (2009). Early healing of nanothickness bioceramic coatings on dental implants. An experimental study in dogs. Journal of Biomedical Materials Research. Part B, Applied Biomaterials 88(2): 387-93.
Abstract: Thick bioceramic coatings like plasma sprayed hydroxyapatite have been shown to increase the overall tissue response and biomechanical fixation of dental implants. However, the presence and potential fracture of a bone-coating-metallic substrate interface at long times after implantation led these implants to fall from favor in clinical practice. The purpose of this study was to evaluate the biomechanical fixation and biological response of Ca- and P-based, 20-50 nm thickness bioceramic deposition on a previously alumina-blasted/acid-etched Ti-6Al-4V implant surface in a dog model. Cylindrical alumina-blasted/acid-etched (AB/AE) (Control, n = 16), and Nanothickness bioceramic coated AB/AE(Nano, n = 16) implant surfaces were surgically placed in dogs proximal tibia and remained for 2 and 4 weeks in vivo. Following euthanization, the implants-in-bone were mounted in epoxy and pullout at a 0.5 mm/min rate. Following mechanical testing, the specimens were decalcified and processed (Hematoxylin and Eosin) for standard transmitted light microscopy evaluation. Percent bone-to-implant contact (BIC) to the pulled out implant surface was determined through computer software. Statistical analyses were performed by one-way ANOVA at 95% level of significance and Tukey's post-hoc multiple comparisons. No significant differences in pullout force were observed (p > 0.88): 2W Control (212.08 +/- 42.96 N), 2W Nano (224.35 +/- 42.97 N), 4W Control (207.07 +/- 42.97 N), and 4W Nano (190.15 +/- 45.94 N). No significant differences in %BIC were observed (p > 0.94): 2W Control (72.66 +/- 8.51), 2W Nano (69.44 +/- 8.51), 4W Control (70.44 +/- 8.51), and 4W Nano (69.11 +/- 9.09). It is shown that 20-50 nm thickness bioceramic depositions onto previously alumina-blasted/acid-etched substrates did not improve the biomechanical fixation and the BIC at early implantation times, and studies concerning shorter and longer implantation times are recommended for confirmation or before a conclusion can be made. Copyright 2008 Wiley Periodicals, Inc.
Descriptors: dental implants, dental porcelain chemistry, dental porcelain metabolism, nanostructures chemistry, wound healing, bone and bones metabolism, dogs, microscopy, electron, scanning, models, animal, nanostructures ultrastructure, stress, mechanical, time factors.
Conner, K.A., R. Sabatini, B.L. Mealey, V.J. Takacs, M.P. Mills, and D.L. Cochran (2003). Guided bone regeneration around titanium plasma-sprayed, acid-etched, and hydroxyapatite-coated implants in the canine model. Journal of Periodontology 74(5): 658-668. ISSN: 0022-3492.
Abstract: Background: Endosseous dental implants with rough surfaces have been designed to improve early healing, especially in areas of poor bone or insufficient bone quantity. The aim of this study was to histomorphometrically assess the bone-to-implant contact on 3 different rough-surfaced implants following guided bone regeneration. Methods: Mandibular premolars and first molars were extracted in 12 dogs, and healing was allowed for 6 months. Six implant osteotomy sites were prepared, 3 per side, followed by the creation of 7.3 mm wide by 5 mm deep surgical defects in the coronal section of the osteotomy sites. Ten-mm long titanium screw-type implants with titanium plasma-sprayed (TPS), hydroxyapatite-coated (HA), or acid-etched (AE) surfaces were placed; the surrounding defects were filled with canine demineralized freeze-dried bone allograft; implants/grafts were covered with expanded polytetrafluoroethylene membranes; and the tissue was closed. Following a healing period of 4 months, the animals were sacrificed and mandibular blocks were harvested for histomorphometric analysis. Results: The mean percentage of bone-to-implant contact in the defect and non-defect areas for the different implant surfaces was: AE 16.24% defect, and 28.78% non-defect; TPS 25.08% defect, and 16.96% non-defect; and HA 48.25% defect and 26.60% non-defect. Within the defect, the mean difference in the bone-to-implant contact was significant for HA compared to TPS (P<0.0001) and HA versus AE (P<0.0001); TPS versus AE was not significant (P=0.063). In the non-defect areas, the mean difference in the bone-to-implant contact was significant for AE versus TPS (P=0.010); all other comparisons were not significant. There were 18 membrane exposures in the 72 implant sites. Data were analyzed again to assess the impact of membrane complications. Using a 1-way analysis of variance, the bone-to-implant contact was compared between the sites with and without membrane complications. No significant differences were seen in the defect areas or in the non-defect areas between the sites with and without membrane complications. Conclusion: In this study, the bone-to-implant contact in regenerated bone was greatest when an HA-coated implant was used.
Descriptors: biomaterials, dental and oral system, ingestion and assimilation, methods and techniques, skeletal system, movement and support, dental implants, prosthetic, guided bone regeneration, clinical techniques, therapeutic and prophylactic techniques, histomorphometric analysis, histology and cytology techniques, laboratory techniques, one way analysis of variance, mathematical and computer techniques, polytetrafluoroethylene membranes, prosthetic, titanium plasma sprayed acid etched hydroxyapatite coated implants, prosthetic, bone to implant contact, follow up studies, membrane complications.
Cutando, A., G. Gomez Moreno, C. Arana, G. Escames, and D. Acuna Castroviejo (2007). Melatonin reduces oxidative stress because of tooth removal. Journal of Pineal Research 42(4): 419-20. ISSN: 0742-3098.
Descriptors: melatonin therapeutic use, oxidative stress drug effects, tooth extraction adverse effects, dogs, gingiva drug effects, gingiva metabolism, glutathione metabolism, lipid peroxidation drug effects, melatonin administration and dosage, models, animal, reactive nitrogen species metabolism.
Dogan, A., A. Ozdemir, A. Kubar, and T. Oygur (2003). Healing of artificial fenestration defects by seeding of fibroblast-like cells derived from regenerated periodontal ligament in a dog: a preliminary study. Tissue Engineering 9(6): 1189-1196. ISSN: 1076-3279.
Abstract: The purpose of this study was to assess the seeding of fibroblast-like cells to promote periodontal healing in artificial fenestration defects in a dog. Fibroblast-like cells were cultured by incubating regenerated periodontal ligament tissue, that had been surgically taken, underneath a Teflon membrane. Fenestration defects were surgically induced on the maxillary canine and first molar teeth at a spacing of 5 to 5 mm. Passage 4 cells (2X105 cells) in autologous blood coagulum were placed on root surfaces in two defects; the remaining two defects were used as controls. Healing was evaluated histomorphometrically on postoperative day 42. The main periodontal healing pattern consisted of connective tissue adaptation in three of the four specimens including one control, with cementum formation at 9-12%; one control specimen that exhibited 100% cementum formation. New bone formation was greater in the cell-seeding group (84%) compared with control (39%). In the cell-seeding group, one specimen exhibited total regeneration of bone (100%); however, the connective tissue located between newly formed bone and the root surface was observed to adapt to the dentin surface, with limited cementum formation. Seeding of cells from periodontal ligament may be promising to promote periodontal regeneration, but needs to be investigated in further studies.
Descriptors: dental and oral system, ingestion and assimilation, skeletal system, movement and support, artificial fenestration defects, healing, preliminary study.
Ebadian, B., M. Razavi, S. Soleimanpour, and R. Mosharraf (2008). Evaluation of tissue reaction to some denture-base materials: an animal study. Journal of Contemporary Dental Practice 9(4): 67-74.
Abstract: AIM: Controversy continues regarding the biocompatibility of denture base materials. One method to evaluate the biocompatibility of materials is in an animal study. Using dogs as subjects, the purpose of this study was to evaluate the vestibular tissue reaction to cobalt chromium (Co-Cr), heat cure acrylic resin, and acrylic resin mixed with aluminum oxide (Al2O3) compared with a control group using the histopathologic method. METHODS AND MATERIALS: Twelve disk shape samples (2 mm x 8 mm) in four groups of Co-Cr, acrylic resin, acrylic resin mixed with a 20% weight ratio of Al2O3, and a control group (Teflon) were fabricated. In one stage surgery two samples of each material (8 samples) was implanted in the buccal vestibule of each dog (n=6), subcutaneously. At 45 and 90-day intervals, half of the samples were excised along with peripheral tissue to assess the presence of inflammation by grading on a scale from 0 to 3 and the presence of a fibrotic capsule using histological observations. Data were analyzed using the Kruskal-Wallis, Mann-Whitney, and Tau b Kendal tests. RESULTS: Tissue reaction between Co-Cr and the control group was significant (P=0.02), but it was not significant between other groups. There was no significant difference between the 45 and 90-day post-insertion samples. The formation of fibrotic capsule groups was significant (P=0.01). It was significant between the Co-Cr and acrylic resin groups (P=0.01) and the acrylic resin and control groups (P=0.01). CONCLUSION: The Co-Cr group was more toxic than the other groups. The inflammation increased during time. The inflammation in two acrylic groups was greater than the control and less than the Co-Cr group. The formation of fibrotic capsule, except in the acrylic resin with Al2O3 group, increased over time. CLINICAL SIGNIFICANCE: Co-Cr alloys are toxic and can produce damage to living tissue. Heat cure acrylic resin materials have less toxicity, and their use is safer than Co-Cr alloys.
Descriptors: biocompatible materials chemistry, dental materials chemistry, denture bases, acrylic resins chemistry, aluminum oxide chemistry, biocompatible materials toxicity, chromium alloys chemistry, chromium alloys toxicity, dental materials toxicity, dental polishing, dogs, fibroblasts pathology, fibrosis, lymphocytes pathology, macrophages pathology, materials testing, methylmethacrylates chemistry, models, animal, mouth mucosa pathology, neutrophils pathology, plasma cells pathology, polytetrafluoroethylene chemistry, random allocation, stomatitis pathology, surface properties, time factors.
Franco, R.L., R. Chiesa, P.T. de Oliveira, M.M. Beloti, and A.L. Rosa (2008). Bone response to a Ca- and P-enriched titanium surface obtained by anodization. Brazilian Dental Journal 19(1): 15-20.
Abstract: This study evaluated bone response to a Ca- and P- enriched titanium (Ti) surface treated by a multiphase anodic spark deposition coating (BSP-AK). Two mongrel dogs received bilateral implantation of 3 Ti cylinders (4.1 x 12 mm) in the humerus, being either BSP-AK treated or untreated (machined - control). At 8 weeks postimplantation, bone fragments containing the implants were harvested and processed for histologic and histomorphometric analyses. Bone formation was observed in cortical area and towards the medullary canal associated to approximately 1/3 of implant extension. In most cases, in the medullary area, collagen fiber bundles were detected adjacent and oriented parallel to Ti surfaces. Such connective tissue formation exhibited focal areas of mineralized matrix lined by active osteoblasts. The mean percentages of bone-to-implant contact were 2.3 (0.0-7.2 range) for BSP-AK and 0.4 (0.0-1.3 range) for control. Although the Mann-Whitney test did not detect statistically significant differences between groups, these results indicate a trend of BSP-AK treated surfaces to support contact osteogenesis in an experimental model that produces low bone-to-implant contact values.
Descriptors: calcium chemistry, coated materials, biocompatible chemistry, dental implants, dental materials chemistry, electroplating methods, humerus pathology, phosphorus chemistry, titanium chemistry, bone marrow pathology, bone remodeling physiology, collagen, connective tissue pathology, dental prosthesis design, dogs, electron probe microanalysis, humerus surgery, microscopy, electron, scanning, models, animal, osseointegration physiology, osteoblasts pathology, osteoclasts pathology, osteogenesis physiology, oxygen analysis, porosity, surface properties.
Freire, J.N., N.R. Silva, J.N. Gil, R.S. Magini, and P.G. Coelho (2007). Histomorphologic and histomophometric evaluation of immediately and early loaded mini-implants for orthodontic anchorage. American Journal of Orthodontics and Dentofacial Orthopedics Official Publication of the American Association of Orthodontists, Its Constituent Societies, and the American Board of Orthodontics 131(6): 704.e1-9.
NAL Call Number: RK1
Abstract: INTRODUCTION: The purpose of this study was to evaluate the bone response to statically loaded 2.5-mm diameter mini-implants of 6 and 10 mm lengths activated after various healing periods in a dog model. METHODS: Seventy-eight machined-surface Ti-6Al-4V mini-implants were bilaterally placed in the mandibular premolar and molar regions of 6 beagle dogs. The left (experimental) and the right (control) hemi-arches received 6 and 7 mini-implants, respectively. Experimental mini-implants healing periods of 0 days (immediately activated), 1 week, and 3 weeks were followed by a 12-week load activation period (250 g between parallel implant pairs). Control (nonloaded) mini-implant groups were placed for 12 weeks, 3 weeks, and 1 week before the dogs were killed they provided data concerning the experimental groups' bone to mini-implant scenarios at load activation times. The mandibles were exposed by sharp dissection, and decalcified specimens were prepared for histomorphologic and histomorphometric (bone to mini-implant contact) assessment. RESULTS: Survival rates were 100% and 77.78% for the control and the experimental groups, respectively. Survival rates were 88.89% for the 10-mm and 66.67% for the 6-mm experimental groups. All failed devices had tissue inflammation and were lost after spring placement. The control groups showed classic bone-healing events, and the experimental groups showed mature bone morphology after 12 weeks in vivo regardless of placement time before load activation. Bone to implant contact values were not significantly different between the experimental and the control groups that remained 12 weeks in vivo. CONCLUSIONS: These results showed that low-intensity immediate or early orthodontic static loads did not affect mini-implant performance.
Descriptors: dental implants adverse effects, dental stress analysis, orthodontic anchorage procedures instrumentation, osseointegration, analysis of variance, dental alloys, dental implantation, endosseous adverse effects, dental prosthesis design, dogs, mandible surgery, miniaturization, models, animal, orthodontic anchorage procedures adverse effects, periodontitis etiology, time factors, titanium, wound healing.
He, Y., Z.Y. Zhang, H.G. Zhu, W. Qiu, X. Jiang, and W. Guo (2007). Experimental study on reconstruction of segmental mandible defects using tissue engineered bone combined bone marrow stromal cells with three-dimensional tricalcium phosphate. Journal of Craniofacial Surgery 18(4): 800-5. ISSN: 1049-2275.
Abstract: Reconstructive procedures of segmental mandible defects often require bone graft harvesting, which results in donor site morbidity; the use of tissue-engineered bone might mitigate this problem. The aim of the present experimental pilot study was to produce three-dimensional (3D) autologous tissue-engineered constructs that combine autogenous cultivated bone marrow stromal cells with beta-tricalcium phosphate to reconstruct segmental mandible defects without donor site morbidity. Bone marrow stromal cells were isolated from a dog's caput femoris. After differentiation and proliferation in vitro, the cells were seeded into a 3D beta-tricalcium phosphate scaffold. The constructs were incubated under osteogenic culture conditions for 5 days. Segmental defects of 30 mm length were created unilaterally in the mandibles of the animals. Reconstruction was performed using the construct in three dogs and the scaffold only in three dogs as a control group. The specimens were retrieved 3 months later, and the reconstructed areas were processed for gross observation, radiographic examination, 3D computed tomographic (CT) imaging, biomechanical evaluations, and histologic observation. The construct implanted group (n = 3) showed an average height of the reconstructed area of 18.54 mm and the control group 9.16 mm (P < 0.05). Higher radiodensity was present in the construct group than in the control group, as shown by radiograph. 3D CT imaging showed nearly two-thirds absorption of the reconstructed area in the control group. The biomechanical examination of the construct and control groups showed a compression strength of 102.77 N and 42.90 N and stress of 3.504 N/mm and 1.930 N/mm, which demonstrates significant difference. Histologic micrographs showed new bone formation in the scaffolds in central sections of the defects in the construct group 3 months later, with osteoblast seams, osteoclastic resorption, and cartilage formation. The construct of morphologic, 3D beta-tricalcium phosphate scaffold seeded, autologous bone marrow stromal cells ensure bone formation and vascularization throughout the procedure of mandible segmental defect reconstruction, closely resembling how tissue engineering would be used to reconstruct a segmental mandible defect in the clinical setting.
Descriptors: bone substitutes chemistry, calcium phosphates chemistry, mandible surgery, oral surgical procedures methods, tissue engineering methods, dogs, mandible cytology, models, animal, pilot projects, stromal cells.
Lee, H.J., B.H. Choi, J.H. Jung, S.J. Zhu, S.H. Lee, J.Y. Huh, T.M. You, and J. Li (2007). Maxillary sinus floor augmentation using autogenous bone grafts and platelet-enriched fibrin glue with simultaneous implant placement. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics 103(3): 329-33.
Abstract: OBJECTIVE: The aim of this study was to evaluate the use of autogenous bone in combination with platelet-enriched fibrin glue as a grafting material for maxillary sinus augmentation with simultaneous implant placement in dogs. STUDY DESIGN: The mucous membranes of 12 sinuses in 6 dogs were elevated bilaterally. In the right sinus, autogenous bone mixed with platelet-enriched fibrin glue was grafted into the space between the membrane and the sinus wall. In the left sinus, autogenous bone alone was grafted as a control. At the same time, 2 dental implants were inserted into the grafting material through the maxillary sinus floor. The animals were killed 6 months after surgery. RESULTS: The mean bone-implant contact was 40.5% on the fibrin glue side and 32.3% on the control side (P < .05). The mean height of newly formed bone in the augmented area was 12.2 mm on the fibrin glue side and 10.7 mm on the control side (P < .05). CONCLUSION: The results indicate that the use of autogenous bone mixed with platelet-enriched fibrin glue can achieve results superior to those for grafts of autogenous bone alone. The specific improvements of this technique include enhanced osseointegration of dental implants and increased height of new bone.
Descriptors: bone regeneration drug effects, bone transplantation methods, dental implantation, endosseous, fibrin tissue adhesive pharmacology, maxillary sinus surgery, oral surgical procedures, preprosthetic methods, platelet rich plasma, dogs, models, animal, statistics, nonparametric.
Marin, C., R. Granato, M. Suzuki, J.N. Gil, A. Piattelli, and P.G. Coelho (2008). Removal torque and histomorphometric evaluation of bioceramic grit-blasted/acid-etched and dual acid-etched implant surfaces: an experimental study in dogs. Journal of Periodontology 79(10): 1942-9. ISSN: 0022-3492.
Abstract: BACKGROUND: Surface modifications to dental implants have been used in an attempt to accelerate the osseointegration process. The objective of this study was to biomechanically/histomorphometrically evaluate a bioceramic grit-blasted and acid-etched surface (BGB/AA; test) versus a dual acid-etched implant surface (control) in a beagle dog model. METHODS: Control and BGB/AA implants were subjected to a series of physicochemical characterization tools, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and auger photoelectron spectroscopy (APS). The animal model included the placement of 72 implants along the proximal tibiae of six beagle dogs, which remained in place for 2 or 4 weeks. After euthanization, half of the specimens were biomechanically tested (removal torque), and the other half was non-decalcified processed to slides of approximately 30 microm thickness for histomorphologic and histomorphometric (percentage of bone-to-implant contact [%BIC]) evaluation. Analysis of variance at the 95% confidence level and the Tukey post hoc test were used for multiple comparisons. RESULTS: SEM and AFM showed that surface microtextures were qualitatively and quantitatively different and that the BGB/AA surface presented higher submicrometer average roughness values (R(a)) and root mean square (RMS) values compared to control surfaces. Ca and P were detected at the BGB/AA surface by APS. Higher degrees of bone organization were observed along the perimeter of the BGB/AA surface compared to control, despite the non-significant differences in %BIC between the surfaces (P >0.25). Significantly higher removal torque was observed for the BGB/AA implants at both time periods (P <0.0001). CONCLUSION: According to the biomechanical and histomorphologic results, early biomechanical fixation was positively affected by the BGB/AA surface compared to the dual-acid etched surface.
Descriptors: acid etching, dental methods, biocompatible materials chemistry, ceramics chemistry, dental etching methods, dental implants, torque, biomechanics, bone remodeling physiology, calcium analysis, carbon analysis, dental prosthesis design, dogs, electron probe microanalysis, materials testing, microscopy, atomic force, microscopy, electron, scanning, models, animal, osseointegration physiology, oxygen analysis, phosphorus analysis, surface properties, tibia pathology, tibia surgery, titanium analysis.
Nethander, G., A. Skoglund, and K.E. Kahnberg (2003). Experimental autogenous tooth transplantation in the dog: a comparison between one- and two-stage surgical techniques. Acta Odontologica Scandinavica 61(4): 223-229. ISSN: 0001-6357.
Abstract: Crucial if tooth transplantation is to succeed is preservation of the vitality of the cells of the periodontium and cementum of the tooth graft. Poor contact between the tissues of the recipient site and the root surface when teeth are transplanted to recipient sites prepared immediately prior to transplantation (one-stage technique) could, after transplantation, result in insufficient nutrition to the cells of the root surface and contribute to necrosis of the cells. To improve nutrition, tooth transplantation to recipient beds left to heal for 14 days was performed (two-stage technique). Clinical trials of tooth transplantation by the two-stage technique resulted in a low incidence of tooth graft loss and root resorption. The different results between these two methods, as well as difficulties in evaluating clinical trials, called for an experimental model to be established. In 5 beagle dogs, fully developed autogenous teeth were transplanted using both one-stage and two-stage surgical techniques. The control teeth were transplanted by the one-stage method to recipient beds prepared immediately before transplantation. The test teeth were transplanted using the two-stage method to recipient beds prepared and left to heal for 5 days prior to transplantation. Four pairs of teeth (1 test and 1 control) were transplanted in each dog. One pair of incisors and one pair of premolars were transplanted in the maxilla and in the mandible. Altogether 20 pairs of teeth were included in the study. One pair of teeth fractured during extraction and was therefore excluded from the study. Two pairs of teeth were lost in the first hours after transplantation. Evaluation of the remaining 17 pairs of teeth was made by routine histological examinations after a 6-month period of healing. The blinded examination failed to show a difference between the two surgical methods in terms of frequency of various types of root resorption. The differences between the results after long-term observation of human teeth transplanted by the one- and two-stage tooth transplantation techniques were not found by this experimental model.
Descriptors: cell biology, dental and oral system, ingestion and assimilation, methods and techniques, root resorption, dental and oral disease, autogenous tooth transplantation, experimental surgical techniques, laboratory techniques, histology, histology and cytology techniques, laboratory techniques, one stage surgical treatment, two stage surgical treatment, experimental surgical techniques, laboratory techniques, cell nutrition, cell vitality, clinical trials, disease frequency, experimental model, necrosis, recipient site, technique comparison, tissue contact, tooth graft loss, wound healing.
Novaes, A.B.J., A.M. Marcaccini, S.L. Souza, M.J. Taba, and M.F. Grisi (2003). Immediate placement of implants into periodontally infected sites in dogs: a histomorphometric study of bone-implant contact. The International Journal of Oral and Maxillofacial Implants 18(3): 391-8. ISSN: 0882-2786.
Abstract: PURPOSE: The placement of implants allows for re-establishment of function and esthetics following tooth loss. Immediate implant placement is a relatively recent procedure and has advantages, such as reduced number of surgical procedures, preservation of alveolar bone, reduction of cost and period of edentulism, and increased patient acceptance. However, there are some specific contraindications for the technique, such as the presence of an infection caused by periodontal disease and periapical lesions. The objective of this study was to evaluate the percentage of bone-implant contact of immediate implants placed in periodontally infected sites. MATERIALS AND METHODS: In the first phase, periodontitis was induced with ligatures in the mandibular premolars of 5 mongrel dogs, using the contralateral teeth as controls (received prophylaxis only). After 3 months, in the second phase of the study, 40 implants were placed in the alveoli of both experimental and control teeth. After a healing period of 12 weeks, the animals were euthanized, and the hemimandibles were removed, dissected, fixed, and prepared for histomorphometric analysis of percentage of bone-implant contact. The Mann-Whitney test was used for statistical analysis. RESULTS: The results of the histomorphometric analysis indicated mean bone-implant contact of 62.4% in the control group and 66.0% in the experimental group, a difference that was not statistically significant. DISCUSSION: Histomorphometric results revealed similar bone-implant contact in both groups, with no signs of infection. CONCLUSIONS: It was concluded that periodontally infected sites may not be a contraindication for immediate implantation in this animal model system, if adequate pre- and postoperative care is taken.
Descriptors: animal model, implants, tooth loss, alveolar bone, pre and postoperative care.
Pearce, A.I., R.G. Richards, S. Milz, E. Schneider, and S.G. Pearce (2007). Animal models for implant biomaterial research in bone: a review. European Cells and Materials 13: 1-10.
NAL Call Number: R857.M3 E97
Abstract: Development of an optimal interface between bone and orthopaedic and dental implants has taken place for many years. In order to determine whether a newly developed implant material conforms to the requirements of biocompatibility, mechanical stability and safety, it must undergo rigorous testing both in vitro and in vivo. Results from in vitro studies can be difficult to extrapolate to the in vivo situation. For this reason the use of animal models is often an essential step in the testing of orthopaedic and dental implants prior to clinical use in humans. This review discusses some of the more commonly available and frequently used animal models such as the dog, sheep, goat, pig and rabbit models for the evaluation of bone-implant interactions. Factors for consideration when choosing an animal model and implant design are discussed. Various bone specific features are discussed including the usage of the species, bone macrostructure and microstructure and bone composition and remodelling, with emphasis being placed on the similarity between the animal model and the human clinical situation. While the rabbit was the most commonly used of the species discussed in this review, it is clear that this species showed the least similarities to human bone. There were only minor differences in bone composition between the various species and humans. The pig demonstrated a good likeness with human bone however difficulties may be encountered in relation to their size and ease of handling. In this respect the dog and sheep/goat show more promise as animal models for the testing of bone implant materials. While no species fulfils all of the requirements of an ideal model, an understanding of the differences in bone architecture and remodelling between the species is likely to assist in the selection of a suitable species for a defined research question.
Descriptors: bone substitutes, implants, experimental, materials testing, models, animal, bone remodeling, bone and bones anatomy and histology, dogs, goats anatomy and histology, rabbits, sheep anatomy and histology, swine anatomy and histology.
Ren, A., T. Lv, N. Kang, B. Zhao, Y. Chen, and D. Bai (2007). Rapid orthodontic tooth movement aided by alveolar surgery in beagles. American Journal of Orthodontics and Dentofacial Orthopedics Official Publication of the American Association of Orthodontists, Its Constituent Societies, and the American Board of Orthodontics 131(2): 160.e1-10.
Abstract: INTRODUCTION: It has been reported that oral surgery can accelerate orthodontic tooth movement. The purpose of this study was to evaluate the effects of alveolar surgery that undermines interseptal bone in orthodontic tooth movement. METHODS: Ten male beagles, aged 12 to 15 months, were used in this study. Extraction of the mandibular second premolar and alveolar surgery to reduce the osteal resistance on the mesial side of the extraction socket were performed on the experimental side; on the control side, only the second premolar was extracted. The first premolars were distalized against the third premolars with orthodontic nickel-titanium coil springs on the both sides. The beagles were killed in the first, second, third, fourth, and eighth weeks after orthodontic force application. RESULTS: The first premolar on the experimental side moved more rapidly than that on the control side (P <.01). Tissue slices were obtained for histological evaluation. No obvious root resorption and no irreversible injury to the pulp were observed on either side. Active and extensive bone resorption in the compressive area and bone deposition in the tension area were observed on the experimental sides. CONCLUSIONS: Self-fluorescence checks showed that more new bone was deposited in the tension area of the experimental side than on the control side (P <.05). These results suggest that alveolar surgery might be an effective and safe way to aid orthodontic tooth movement.
Descriptors: bicuspid surgery, molar, tooth movement methods, tooth socket surgery, bicuspid radiography, bone regeneration physiology, dogs, fluorescence, models, animal, root resorption radiography, time factors, tooth extraction, tooth socket metabolism.
Saito, E., A. Saito, and M. Kawanami (2003). Favorable healing following space creation in rhbmp-2-induced periodontal regeneration of horizontal circumferential defects in dogs with experimental periodontitis. Journal of Periodontology 74(12): 1808-1815. ISSN: 0022-3492.
Abstract: Background: Recombinant human bone morphogenetic protein-2 (rhBMP-2) is believed to be capable of inducing periodontal regeneration. However, the risk of aberrant healing events, such as root resorption and ankylosis, has been reported. We hypothesized that implantation of BMP-containing carriers directly on the root planed surface may be the cause of unfavorable healing. The purpose of this study was to evaluate the influence of a 1 mm spacer membrane, which separated the rhBMP-2 in polymer-coated gelatin sponge (PGS) and the root surface, on periodontal regeneration of experimentally induced horizontal defects in dogs. Methods: Horizontal circumferential periodontal defects were surgically created, and experimental periodontitis was induced in 72 maxillary and mandibular premolars of four male beagle dogs. The recipient sites of each quadrant received: 1) rhBMP-2/PGS (B group) (rhBMP-2 at 1.0 mg/ml, total implant volume/site apprx7.2 mul) (n=24); 2) rhBMP-2/PGS with a spacer membrane (PB group) (n=24); and 3) physiological saline (PS)/PGS as a control (P group) (n=24). One quadrant was left untreated. Dogs were sacrificed at 12 weeks post-surgery, and healing was evaluated histologically. Results: Both groups treated with rhBMP-2/PGS demonstrated enhanced new bone formation and connective tissue attachment with cementum regeneration when compared to the control group. Sites treated with rhBMP-2/PGS showed a greater degree of bone formation than sites treated with rhBMP-2/PGS and spacer membrane, although the latter sites showed no ankylosis. Conclusions: Implantation of rhBMP-2/PGS enhances bone formation and connective tissue attachment in horizontal circumferential defects. In addition, the use of a spacer membrane reduces the degree of bone formation, but minimizes ankylosis.
Descriptors: biochemistry and molecular biophysics, dental and oral system, ingestion and assimilation, skeletal system, movement and support, periodontitis, dental and oral disease, diagnosis, therapy, horizontal circumferential defect, periodontal regeneration, wound healing.
Schliephake, H., D. Scharnweber, M. Dard, S. Roessler, A. Sewing, and C. Huettmann (2003). Biological performance of biomimetic calcium phosphate coating of titanium implants in the dog mandible. Journal of Biomedical Materials Research 64A(2): 225-234. ISSN: 0021-9304.
NAL Call Number: R856.J6
Abstract: The aim of the present study was to analyze the in vivo effect of biomimetic calcium phosphate coating of titanium implants on periimplant bone formation and bone-/implant contact. Five types of implants were used: 1) Ti6Al4V implants with a polished surface; 2) Ti6Al4V implants with collagen coating; 3) Ti6Al4V implants with a mineralized collagen layer; 4) Ti6Al4V implants with sequential coating of hydroxyapatite (HA) and collagen; and 5) Ti6Al4V implants with HA coating only. All implants had square cross sections with an oblique diameter of 4.6 mm and were inserted press fit into trephine burr holes of 4.6 mm in the mandibles of ten beagle dogs. The implants of five animals each were evaluated after a healing period of 1 month and 3 months, respectively, during which time sequential fluorochrome labeling of bone formation had been performed. Bone formation was evaluated by morphometric measurement of the newly formed bone around the implants and the percentage of implant bone contact. After 1 month, there was a significantly higher percentage of mean bone/implant contact in the HA-coated implants compared to those with polished surface and those with the collagen-coated surface. After 3 months, these differences were not present anymore. Bone apposition was significantly higher next to implants with sequential HA/collagen coating compared to polished surfaces and mineralized collagen layer. It is concluded that biomimetic coating of titanium implants with HA has shown the clearest trend to increase bone-implant contact in the early ingrowth period. The addition of collagen to an HA coating layer may hold some promise when used as sequential HA/collagen coating with mineralized collagen as the surface layer.
Descriptors: biomaterials, dental and oral system, ingestion and assimilation, skeletal system, movement and support, titanium implant, medical equipment, bone formation, cell adhesion, osseointegration, periimplant bone formation.
Shi, B., Y. Zhou, Y.N. Wang, and X.R. Cheng (2007). Alveolar ridge preservation prior to implant placement with surgical-grade calcium sulfate and platelet-rich plasma: a pilot study in a canine model. International Journal of Oral and Maxillofacial Implants 22(4): 656-65. ISSN: 0882-2786.
Abstract: PURPOSE: To evaluate the combination of surgical-grade calcium sulfate (SGCS) and platelet-rich plasma (PRP) for alveolar ridge preservation prior to implant placement. MATERIALS AND METHODS: Five mongrel dogs were used as subjects. Four enlarged mandibular extraction sockets, 2 on each side, were created in each dog. According to a split-mouth design, the 2 anterior sockets received either SGCS/PRP (SGCS/PRPant) or were left unfilled, while the 2 posterior sockets received either SGCS/PRP (SGCS/PRPpost) or SGCS. Computerized tomographic (CT) scans were conducted at 1 day and 8 weeks postextraction to detect the change in ridge height. Bone scintigraphy was performed at 2, 4, and 6 weeks to investigate new bone formation activity. At 8 weeks, 1 dog was sacrificed for histologic and histomorphometric study. Meanwhile, implants were placed in the remaining 4 dogs. These 4 dogs were sacrificed after 3 months. RESULTS: Less ridge resorption was observed in the anterior SGCS/PRP-filled sites compared to unfilled sites (P = .001), while no significant difference was found between the SGCS/PRPpost and SGCS groups (P = .544). Bone scintigraphy showed that sites filled with SGCS/PRP showed significantly higher count/pixel at 2 (P = .028), 4 (P = .009), and 6 weeks (P = .037) than the unfilled sites. Nevertheless, the SGCS/PRPpost group achieved significantly higher values than the SGSC group only at 2 weeks (P = .036). Histomorphometrically, the SGCS/PRPant group showed a significantly higher percentage of bone-implant contact than the unfilled group (P = .024), but no significant difference was detected between the SGCS/PRPpost and SGCS groups (P = .979). CONCLUSION: Grafting SGCS/PRP in fresh extraction sockets reduced alveolar ridge resorption and promoted the bone formation in this canine model. The addition of PRP to SGCS resulted in the enhancement of bone regeneration in the early phase of healing.
Descriptors: alveolar process surgery, bone substitutes therapeutic use, calcium sulfate therapeutic use, dental implants, mandible surgery, platelet rich plasma, alveolar bone loss prevention and control, alveolar process pathology, bone regeneration physiology, bone resorption prevention and control, dogs, mandible pathology, models, animal, osseointegration physiology, osteogenesis physiology, pilot projects, radiopharmaceuticals diagnostic use, technetium tc 99m medronate diagnostic use, time factors, tomography, x ray computed, tooth extraction, tooth socket pathology, tooth socket surgery.
Sperandio, C.B., L.F. Silveira, L.A. de Araujo, J. Martos, and A. Malshe (2008). Response of the periapical tissue of dogs' teeth to the action of citric acid and EDTA. Journal of Applied Oral Science Revista FOB 16(1): 59-63.
Abstract: The purpose of this study was to analyze the inflammatory response of dog's periapical tissues to 17% trisodium EDTA salt (pH 8.0) and 1% citric acid (pH 2.0). Saline was used as a control. Six adult dogs were used as the biological model of the study. The experimental units comprised 56 roots of mandibular molars (first and second) and premolars (first, second and third). After coronal opening, pulpectomy and root canal instrumentation were performed using the above-mentioned irrigating solutions. After 24 and 48 hours, the animals were euthanized and the teeth and their supporting tissues were removed and histologically processed. The sections were stained with hematoxylin and eosin and analyzed histopathologically with a light microscope at x100 magnification. The histological analysis focused on the occurrence of acute inflammatory response. The presence of swelling, vasodilatation and inflammatory cells were evaluated and the degree of inflammation was determined for each case. Data were analyzed by Fisher's exact test using the SPSS software with a confidence interval of 95% (p<0.05). 17% EDTA and 1% citric acid caused inflammatory responses in dog's periapical tissues with no significant differences to each other or to saline (control) at either the 24-hour (p=0.482) or 48-hour (p=0.377) periods. It may be concluded that the inflammatory response was of mild intensity for the tested substances.
Descriptors: biocompatible materials therapeutic use, citric acid therapeutic use, edetic acid therapeutic use, periapical tissue drug effects, root canal irrigants therapeutic use, bicuspid pathology, dogs, edema chemically induced, edema pathology, models, animal, molar pathology, periapical periodontitis chemically induced, periapical periodontitis pathology, periapical tissue pathology, pulpectomy methods, root canal preparation instrumentation, root canal preparation methods, time factors, vasodilation drug effects.
Tomofuji, T., D. Ekuni, T. Yamamoto, M. Horiuchi, T. Sakamoto, and T. Watanabe (2003). Optimum force and duration of toothbrushing to enhance gingival fibroblast proliferation and procollagen type i synthesis in dogs. Journal of Periodontology 74(5): 630-634. ISSN: 0022-3492.
Abstract: Background: Toothbrushing enhances gingival fibroblast proliferation, which promotes wound healing. Optimum force and duration of toothbrushing for stimulation of fibroblast proliferation are key factors in maximizing effects of toothbrushing on periodontal wound healing. We therefore evaluated the effects of different durations and forces of toothbrushing on proliferative activity and procollagen synthesis of gingival fibroblasts. Methods: Twelve dogs were used. In each dog, buccal gingivae of 12 teeth were examined for 3 weeks. Nine of these 12 teeth were each assigned to 1 of 9 different combinations of brushing force (0.98, 1.96, or 2.45 N) and duration (10, 20, or 40 seconds). The remaining 3 teeth received plaque removal without brushing, via a scaler. Results: Force and duration of toothbrushing affected both proliferating cell nuclear antigen (PCNA)-positive and procollagen Type I C-peptide (PIP)-positive fibroblast ratios (P<0.05). The highest ratio of PCNA-positive fibroblasts was produced by brushing at 1.96 N for 20 seconds. The highest ratio of PIP-positive fibroblasts was produced by brushing at 1.96 N for 10 seconds. Conclusions: Toothbrushing at certain forces and durations enhanced the proliferative activity and procollagen synthesis of gingival fibroblasts. The toothbrushing duration that increased procollagen synthesis (10 seconds) was shorter than that which increased fibroblast proliferative activity (20 seconds).
Descriptors: dental and oral system, ingestion and assimilation, methods and techniques, periodontal wound healing, toothbrushing, optimum force, duration.
Toomarian, L., R. Fekrazad, D. Sharifi, M. Baghaei, H. Rahimi, and B. Eslami (2008). Histopathological evaluation of pulpotomy with Er,Cr:YSGG laser vs formocresol. Lasers in Medical Science 23(4): 443-50. ISSN: 0268-8921.
Abstract: The purpose of this study was to histologically investigate whether pulpotomy with Er,Cr:YSGG laser is an acceptable alternative for formocresol. Pulpotomy of 48 dog's primary canine teeth was performed with formocresol or Er,Cr:YSGG laser. Histological evaluations on hematoxylin and eosin-stained pulp tissues were made by an optical microscope 7 or 60 days later. Statistical analysis was performed with Fisher's exact test, Mann-Whitney U test, and Student's t test. Seven days after pulpotomy, samples treated with laser had significantly favorable histological features in the following measures: continuity of odontoblastic layer (P<0.001), presence of hemorrhage (P<0.008), amount of inflammation (P<0.002), tissue necrosis (P<0.001), internal resorption (P<0.002), level of vascularization (P<0.002), and size of abscess (P<0.041). Similar results were observed 60 days after pulpotomy, except that the differences were not mostly significant due to natural exfoliation of 16 teeth. In conclusion, Er,Cr:YSGG laser system is an acceptable alternative for formocresol in pulpotomy of deciduous teeth.
Descriptors: dental pulp radiation effects, formocresols therapeutic use, hematoxylin radiation effects, laser therapy instrumentation, lasers, solid state, pulpotomy instrumentation, tooth, deciduous radiation effects, dental pulp drug effects, dogs, laser therapy methods, models, animal, odontoblasts radiation effects, pilot projects, pulpotomy methods, zinc oxide.
van Leeuwen, E.J., J.C. Maltha, A.M. Kuijpers Jagtman, and M.A. Van't Hof (2003). The effect of retention on orthodontic relapse after the use of small continuous or discontinuous forces. An experimental study in beagle dogs. European Journal of Oral Sciences 111(2): 111-116. ISSN: 0909-8836.
Abstract: Relapse is a major concern in orthodontics for which avoidance retention is the general procedure. However, the effect of retention on relapse after active tooth movement with different force regimes has never been studied in a standardized experimental setting. Mandibular third premolars were extracted in 19 young adult beagle dogs. Three months later, the second premolars were bodily moved distally with forces of 10 cN or 25 cN. The forces were applied for 24 h d-1 or for 16 h d-1. After 4 months, relapse was allowed in half of the animals, while in the others relapse was preceded by retention for 90 d. Statistical analyses were performed on the relation between force regime, active tooth movement, retention, and relapse. Force magnitude had no effect on relapse, while continuous forces resulted in a longer-lasting and more pronounced relapse than did discontinuous forces. A significant positive correlation was found between the amount of active tooth movement and both the rate and the total amount of relapse, but not between the amount of active tooth movement and the duration of the relapse. Retention had no effect on the duration of the relapse, but it strongly decreased its total amount. Finally, the effect of retention on the amount of relapse was strongly correlated with the amount of active tooth movement.
Descriptors: dental and oral system, ingestion and assimilation, equipment apparatus devices and instrumentation, orthodontic appliance, prosthetic, continuous forces, discontinuous forces, orthodontic relapse, retention.
Yamauchi, K., T. Takahashi, K. Funaki, and Y. Yamashita (2008). Periosteal expansion osteogenesis using highly purified beta-tricalcium phosphate blocks: a pilot study in dogs. Journal of Periodontology 79(6): 999-1005. ISSN: 0022-3492.
Abstract: BACKGROUND: In highly atrophic edentulous jaws, the augmentation of the alveolar process is standard treatment for dental implantation because of the lack of alveolar bone height and width. Our aim was to examine periosteal expansion osteogenesis in a dog model, based on the concept of distraction osteogenesis, using a highly purified beta-tricalcium phosphate (beta-TCP) block instead of an original bone segment. METHODS: Three beagle dogs weighing 10 to 12 kg were used. The beta-TCP block was placed at the lateral surface of the mandibular bone. Two titanium screws were inserted from the lingual aspect to push the block to the buccal side. After a latency period of 8 days, during which primary wound healing occurred, the lingual screws were advanced by approximately 0.5 mm/day for 8 days. Specimens were taken 8 weeks after lingual screw adjustments ceased and were analyzed by hematoxylin and eosin, tartrate-resistant acid phosphatase (TRAP), and Villanueva bone staining. RESULTS: The alveolar form at the experimental region was changed dramatically following lateral expansion with the beta-TCP block. Newly formed bone was observed in the gap between the bone and the beta-TCP block, as well as on the lateral surface of the block. Moreover, the replacement of large parts of beta-TCP with newly formed bone was observed in the beta-TCP block area. However, newly formed bone was not observed over the upper parts of the block, and multinucleated TRAP-positive cells were attached to the beta-TCP in the periphery of this area. CONCLUSION: The highly purified beta-TCP block worked as an activator for the soft tissue, including the periosteum, as well as a space maker to induce an osteoblastic response in the periosteum.
Descriptors: alveolar ridge augmentation methods, bone substitutes, calcium phosphates, osteogenesis, distraction methods, periosteum physiology, dogs, models, animal, osteogenesis, pilot projects.
You, T.M., B.H. Choi, J. Li, F. Xuan, S.M. Jeong, and S.O. Jang (2009). Morphogenesis of the peri-implant mucosa: a comparison between flap and flapless procedures in the canine mandible. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics 107(1): 66-70.
Abstract: OBJECTIVE: Although it has been shown that the exclusion of the mucoperiosteal flap can prevent postoperative bone resorption associated with flap elevation, there have been only a few studies on the peri-implant mucosa following flapless implant surgery. The purpose of this study was to compare the morphogenesis of the peri-implant mucosa between flap and flapless implant surgeries by using a canine mandible model. STUDY DESIGN: In six mongrel dogs, bilateral edentulated flat alveolar ridges were created in the mandible. After 3 months of healing, 2 implants were placed in each side by either the flap or the flapless procedure. Three months after implant insertion, the peri-implant mucosa was evaluated by using clinical, radiologic, and histometric parameters, which included the gingival index, bleeding on probing, probing pocket depth, marginal bone loss, and the vertical dimension of the peri-implant tissues. RESULTS: The height of the mucosa, length of the junctional epithelium, gingival index, bleeding on probing, probing depth, and marginal bone loss were all significantly greater in the dogs that had the flap procedure than in those that had the flapless procedure (P < .05). CONCLUSION: These results indicate that gingival inflammation, the height of junctional epithelium, and bone loss around nonsubmerged implants can be reduced when implants are placed without flap elevation.
Descriptors: dental implantation, endosseous methods, epithelial attachment physiology, mouth mucosa physiology, alveolar bone loss etiology, dental implantation, endosseous adverse effects, dental implants, dogs, epithelial attachment pathology, epithelial attachment surgery, gingivitis etiology, implants, experimental, mandible surgery, models, animal, morphogenesis, mouth mucosa pathology, mouth mucosa surgery, periodontal index, random allocation.
Zhou, H.Z., M. Hu, H.C. Liu, J. Yao, M. Xie, and H.X. Xiao (2003). [Reconstruction of segmental mandibular defect of canine using titanium-nickel distractor]. Zhonghua Kou Qiang Yi Xue Za Zhi. 38(5): 333-5. ISSN: 1002-0098.
Abstract: OBJECTIVE: To establish a continuous and automatic distraction osteogenesis technique in reconstruction of segmental mandibular defect by using embedded titanium-nickel alloy distractor with characteristics of shape-memory and super-elasticity. METHODS: Adult hybrid canines were used as the animal model. Segmental defects of 1-3 cm in the body of mandible were created by surgical osteotomy. Bi-focal distraction osteogenesis was applied using embedded titanium-nickel distractor designed by the authors. The canines were sacrificed 3 months after the operation and the mandibles were harvested to examine the results of bone regeneration. RESULTS: The histocompatibility of titanium-nickel distractors was good. Distraction osteogenesis was completed automatically and the defects were elementarily restored. Radiological and histological examination showed well bone regeneration in distraction area. CONCLUSIONS: Distraction osteogenesis using embedded self-loading titanium-nickel distractor could be a hopeful and useful technique. It might help to solve the problems of functional mandibular reconstruction in the near future.
Descriptors: animal model, segmental mandibular defect, surgical osteotomy, osteogenesis technique, reconstruction, methods, titanium-nickel alloy distractor, super-elasticity.