Influence of cyclosporin A on quality of bone around integrated dental implants: a radiographic study in rabbits

To evaluate the influence of cyclosporin A (CsA) administration on bone around integrated dental implants assessed by a bone quality index and by quantitative subtraction radiography.A total of 36 machine surface commercial implants were placed in 18 adult rabbits. After a 3-month healing period without any disturbance, the animals were randomly divided into three groups of six animals each. Group A was sacrificed at this time. CsA was injected subcutaneously in an immunosuppressive dose of 10 mg/kg/day in a test group (Group T), and a Group B served as a control, receiving only vehicle. After 3 months of cyclosporin administration, the animals of both Groups B and T were sacrificed. Radiographs were obtained at implant surgery and at the day of sacrifice with a CMOS sensor. Bone quality around the implants was compared between the groups using a bone quality index and quantitative subtraction radiography.The bone analysis showed that in Group T, the bone quality changed dramatically from a dense cortical to a loose trabecular bone structure (P < 0.0001, chi(2) test) while in Groups A and B there were no significant differences. Quantitative digital subtraction radiography showed significantly (P < 0.05) lower gray shade values (radiographic density) in a region of bone formation around the implants in Group T (118 +/- 12) than in Groups A (161 +/- 6) and B (186 +/- 10).Within the limits of this study, CsA administration has a negative effect on the quality of bone around integrated dental implant.

Histomorphometric analysis of tissue responses to bioactive glass implants in critical defects in rat calvaria

The aim of this study was to evaluate the osteogenic behavior of two chemically similar bioactive glass products (Biogran (R) and Perioglas (R)) implanted in critical bone defects in rat calvaria. Thirty-six transfixed bone defects of 8 mm diameter were made surgically in adult male Wistar rats. The animals were distributed equally into three groups: Biogran (GI), Perioglas (GII) and without implant material (control; GIII). The morphology and composition of both bioactive glasses were analyzed by scanning electron microscopy and energy-dispersive spectrometry. Tissue specimens were analyzed at the biological time points of 15, 30 and 60 days by optical microscopy and morphometry, demonstrating biocompatibility for the tested materials with moderate chronic inflammation involving their particles. Bone neoformation resulted only as a reparative reaction to an intentionally produced defect and was limited to the defect's edges. No statistically significant differences among the groups were observed. At the scar interstice, abundant deposits of collagenous fibers enveloping the particles were noted. The present results indicated that the bioactive glasses, under the experimental conditions analyzed, did not show osteogenic behavior. Copyright (c) 2007 S. Karger AG, Basel.

Multidisciplinary approach for the aesthetic treatment of maxillary lateral incisors agenesis: thinking about implants?

Missing maxillary lateral incisors create an esthetic problem with specific orthodontic and prosthetic considerations. Implants are commonly used to replace congenitally missing lateral incisors in adolescent orthodontic patients. However, an interdisciplinary approach should be observed during the diagnosis, prognosis, and treatment plan to provide a result with good predictability and meet the esthetic and functional expectations of the patient. The present study describes a case of a young patient with tooth agenesis of maxillary lateral incisors, which was conducted with an integrated planning. After 5-year follow-up of 2 fixed implant-supported prostheses, clinical and radiographic examination showed the treatment to be successful. (Oral Surg Oral Med Oral Pathol Oral Radiol 2012;114:e22-e28)

Gingival Papilla Dimensions in Anterosuperior Regions Adjacent to Single-Tooth Implants

This study compared the dimensions of gingival papillae in anterosuperior areas presenting at natural teeth (teeth sites) or single-tooth implants adjacent to natural teeth (implant-tooth sites) by analyzing determined distances. A total of 45 teeth and 46 implant-tooth sites were carefully selected. Clinical evaluation consisted of visual and quantitative analyses with millimeter grids on radiographs. Implant-tooth sites showed a smaller gingival papilla dimension than tooth sites (P < .01). Both evaluated distances (contact point to bone crest and between the roots of adjacent teeth or implant platform to root of adjacent tooth) in all groups significantly influenced the presence/absence of gingival papillae (P < .01). (Int J Periodontics Restorative Dent 2012;32:93-100.)

Influence of Implant Design on the Biomechanical Environment of Immediately Placed Implants: Computed Tomography-Based Nonlinear Three-Dimensional Finite Element Analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Intrusion of teeth with class III furcation: a clinical, histologic and histometric study in dogs

Aim: To assess orthodontic intrusion effects on periodontal tissues in dogs' pre-molars with class III furcations treated with open flap debridement (OFD) or with guided tissue regeneration (GTR) associated to bone autograft (BA).Material and Methods: Class III furcations were created in the pre-molars of seven mongrel dogs. After 75 days, teeth were randomly treated with OFD or GTR/BA. After 1 month, metallic crowns were assembled on pre-molars and connected apically to mini-implants by nickel-titanium springs. Teeth were randomly assigned to orthodontic intrusion (OFD+I and GTR/BA+I) groups or no movement (OFD and GTR/BA) groups. Dogs were sacrificed after 3 months of movement and 1 month retention.Results: All class III furcations were closed or reduced to class II or I in the intrusion groups, while 50% of the lesions in non-moved teeth remained unchanged. Intruded teeth presented higher probing depth and lower gingival marginal level than non-moved teeth (p < 0.01). Clinical attachment gain was reduced in the intrusion groups by the end of retention (p < 0.05). OFD+I presented smaller soft tissue area and larger bone tissue area than other groups (p < 0.05).Conclusion: Orthodontic intrusion with anchorage via mini-implants improved the healing of class III furcation defects after OFD in dogs. GTR/BA impaired those results.

Early Bone Healing and Biomechanical Fixation of Dual Acid-Etched and As-Machined Implants with Healing Chambers: An Experimental Study in Dogs

Purpose: To evaluate the biomechanical fixation, bone-to-implant contact (BIC), and bone morphology of screw-type root-form implants with healing chambers with as-machined or dual acid-etched (DAE) surfaces in a canine model. Materials and Methods: The animal model included the placement of machined (n = 24) and DAE (n = 24) implants along the proximal tibiae of six mongrel dogs, which remained in place for 2 or 4 weeks. Following euthanasia, half of the specimens were subjected to biomechanical testing (torque to interface failure) and the other half were processed for histomorphologic and histomorphometric (%BIC) assessments. Statistical analyses were performed by one-way analysis of variance at the 95% confidence level and the Tukey post hoc test for multiple comparisons. Results: At 4 weeks, the DAE surface presented significantly higher mean values for torque to interface failure overall. A significant increase in %BIC values occurred for both groups over time. For both groups, bone formation through the classic appositional healing pathway was observed in regions where intimate contact between the implant and the osteotomy walls occurred immediately after implantation. Where contact-free spaces existed after implantation (healing chambers), an intramembranous-like healing mode with newly formed woven bone prevailed. Conclusions: In the present short-term evaluation, no differences were observed in BIC between groups; however, an increase in biomechanical fixation was seen from 2 to 4 weeks with the DAE surface. INT J ORAL MAXILLOFAC IMPLANTS 2011;26:75-82

Influence of estrogen deficiency and its treatment with alendronate and estrogen on bone density around osseointegrated implants: radiographic study in female rats

Objective. This study evaluated the influence of estrogen deficiency and its treatment on bone density around integrated implants.Study design. Implants were placed in female rat tibiae. The animals were assigned to 5 groups: control, sham, ovariectomy, estrogen, and alendronate. The control group was humanely killed to confirm integration of the implant. The others were submitted to ovariectomy or sham surgery. Bone density was measured by digital radiographs at 6 points on sides of the implant.Results. The analysis of radiographic bone density revealed estrogen privation had a negative impact only in the cancellous bone. The estrogen group differed significantly ( P <.05) from the ovariectomy and alendronate groups. The alendronate group presented the highest density for all evaluated regions.Conclusion. Ovariectomy caused a decrease in the radiographic bone density in the cancellous region. Estrogen replacement therapy and alendronate were effective treatments in preventing bone mass loss around integrated implants.

Effect of Drilling Technique on the Early Integration of Plateau Root Form Endosteal Implants: An Experimental Study in Dogs

Purpose: This study tested the hypothesis that early integration of plateau root form endosseous implants is significantly affected by surgical drilling technique.Materials and Methods: Sixty-four implants were bilaterally placed in the diaphysial radius of 8 beagles and remained 2 and 4 weeks in vivo. Half the implants had an alumina-blasted/acid-etched surface and the other half a surface coated with calcium phosphate. Half the implants with the 2 surface types were drilled at 50 rpm without saline irrigation and the other half were drilled at 900 rpm under abundant irrigation. After euthanasia, the implants in bone were nondecalcified and referred for histologic analysis. Bone-to-implant contact, bone area fraction occupancy, and the distance from the tip of the plateau to pristine cortical bone were measured. Statistical analyses were performed by analysis of variance at a 95% level of significance considering implant surface, time in vivo, and drilling speed as independent variables and bone-to-implant contact, bone area fraction occupancy, and distance from the tip of the plateau to pristine cortical bone as dependent variables.Results: The results showed that both techniques led to implant integration and intimate contact between bone and the 2 implant surfaces. A significant increase in bone-to-implant contact and bone area fraction occupancy was observed as time elapsed at 2 and 4 weeks and for the calcium phosphate-coated implant surface compared with the alumina-blasted/acid-etched surface.Conclusions: Because the surgical drilling technique did not affect the early integration of plateau root form implants, the hypothesis was refuted. (C) 2011 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 69: 2158-2163, 2011

Influence of homeopathic treatment with comfrey on bone density around titanium implants. A digital subtraction radiography study in rats

Objective: The objective of this study was to evaluate the influence of homeopathic treatment with comfrey (Shymphytum officinalis 6CH) on radiographic bone density and area around titanium implants.Material and methods: Forty-eight rats were divided into two groups of 24 animals each: a control group (C) and a test group (SO). Each animal received one titanium micro-implant placed in the tibia. The animals in Group SO were subjected to 10 drops of comfrey 6CH per day mixed into their drinking water until the day of sacrifice. Eight animals of each group were sacrificed at 7, 14 and 28 days post-surgery, respectively.Standardized digital radiographs were obtained on the day of implant installation (baseline images) and on the day of sacrifice (final images). Digital subtraction of the two corresponding images was performed to evaluate changes in bone density and the area related to change around the implant between baseline and final images.Results: Subtraction images demonstrated that a significant difference existed in mean shade of gray at 14 days post-surgery between Group SO (mean 175.3 +/- 14.4) and Group C (mean 146.2 +/- 5.2). Regarding the area in pixels corresponding to the bone gain in Group SO, the differences observed between the sacrifice periods and groups were only significant at 7 days sacrifice between Group SO (mean 171.2 +/- 21.9) and Group C (mean 64.5 +/- 60.4).Conclusion: Within the limits of this study, comfrey administration promotes an increase in radiographic bone density around titanium implants in the initial period of bone healing.

Clinical and radiographic changes around dental implants inserted in different levels in relation to the crestal bone, under different restoration protocols, in the dog model

Background: The aim of the present study was to evaluate clinical and radiographic changes that occur around dental implants inserted in different levels in relation to crestal bone under different restoration protocols.Methods: Thirty-six implants were inserted in the edentulous mandible of six mongrel dogs. Each implant was assigned to an experimental group according to the distance from the top of the implant to the crestal bone: Bone Level (at crestal bone level), Minus 1 (1 mm below crestal bone), or Minus 2 (2 mm below crestal bone). Each hemimandible was submitted to a restoration protocol: conventional (prosthesis was installed 120 days after implant placement, including 30 days with healing cap) or immediate (prosthesis was installed 24 hours after implant placement). Fixed partial prostheses were installed bilaterally in the same day. After 90 days, clinical and radiographic parameters were evaluated.Results: As long as the implants were inserted in more apical positions, the first bone-to-implant contact (fBIC) was positioned more apically (P<0.05). However, the apical positioning of the implants did not influence the ridge loss or the position of the soft tissue margin (PSTM) (P>0.05). In addition, in immediately restored sites, the PSTM was located significantly more coronally than that in conventionally restored sites (P=0.02).Conclusions: Despite the more apical positioning of the fBIC, the height of the peri-implant soft tissues and ridge was not jeopardized. Moreover, the immediate restoration protocol was beneficial to the maintenance of the PSTM. Further studies are suggested to evaluate the significance of these results in longer healing periods.

Effect of diabetes mellitus and insulin therapy on bone density around osseointegrated dental implants: a digital subtraction radiography study in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of Severe Dietary Magnesium Deficiency on Systemic Bone Density and Removal Torque of Osseointegrated Implants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of a Fluoridated Medium with Different pHs on Commercially Pure Titanium-Based Implants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Laser ablation in titanium implants followed by biomimetic hydroxyapatite coating: Histomorphometric study in rabbits

Titanium surface texture and chemistry modification successfully improves the host response and consequently the bone-to-implant contact surrounding dental implants. The aim of the present study was to investigate, using histomorphometrical-analysis, the effects of titanium surface modification by laser-ablation (Nd:YAG) followed by thin chemical deposition of HA. Forty-eight rabbits received one implant by tibiae of AS-machined (MS), laser-modified (LMS), or biomimetic hydroxyapatite-coated (HA) surface. Bone-to-implant contact (BIC) and bone area (BBT) were evaluated after 4, 8, and 12 weeks, at cortical and cancellous regions. Average BIC in the cortical region was higher (P < 0.001) on the LMS and HA implants for all periods, with no differences between LMS and HA. For the cancellous area, the LMS and HA implants showed higher (P < 0.01) BIC than MS at the initial periods. The LMS and HA showed similar values in the cortical region, but a tendency of higher values for HA in the cancellous region was observed in all periods. For the BBT, the differences were found only between HA and MS after 4 weeks in the cortical region (P < 0.05), and after 12 weeks in the cancellous area (P < 0.05). Our results showed that HA biomimetic coating preceded by laser treatment induced the contact osteogenesis and allowed the formation of a more stable boneimplant interface, even in earlier periods. Microsc. Res. Tech., 2012. (C) 2012 Wiley Periodicals, Inc.