Darceny Zanetta-Barbosa

Effect of Drilling Dimension on Implant Placement Torque and Early Osseointegration Stages: An Experimental Study in Dogs

PURPOSE Primary stability has been regarded as a key factor to ensure uneventful osseointegration of dental implants. Such stability is often achieved by placing implants in undersized drilled bone. The present study evaluated the effect of drilling dimensions in insertion torque and early implant osseointegration stages in a beagle dog model. MATERIALS AND METHODS Six beagle dogs were acquired and subjected to bilateral surgeries in the radii 1 and 3 weeks before death. During surgery, 3 implants, 4 mm in diameter by 10 mm in length, were placed in bone sites drilled to 3.2 mm, 3.5 mm, and 3.8 mm in diameter. The insertion torque was recorded for all samples. After death, the implants in bone were nondecalcified processed and morphologically and morphometrically (bone-to-implant contact and bone area fraction occupancy) evaluated. Statistical analyses were performed using the Kruskal-Wallis test followed by Dunns post hoc test for multiple comparisons at the 95% level of significance. RESULTS The insertion torque levels obtained were inversely proportional to the drilling dimension, with a significant difference detected between the 3.2-mm and 3.8-mm groups (P = .003). Despite a significant increase in the bone-to-implant contact over time in vivo for all groups (P = .007), no effect for the drilling dimension was observed. Additionally, no effect of the drilling dimension and time was observed for the bone area fraction occupancy parameter (P = .31). The initial healing pathways differed between implants placed in bone drilled to different dimensions. CONCLUSIONS Although different degrees of torque were observed with different drilling dimensions and these resulted in different healing patterns, no differences in the histometrically evaluated parameters were observed.

Retrospective study of bone grafting procedures before implant placement.

Aim:The aim of this retrospective study was to evaluate morbidity and possible complications in augmentation procedures before implant placement. Methods:Records from 93 consecutive patients with indication for autogenous bone grafting before implant placement, treated at Department of Oral and Maxillofacial Surgery and Implantology of Uberlândia Federal University, in a 7-year period (July 2000 until July 2007), were reviewed. The need for bone grafting was defined by the impossibility of installing implants of adequate length or diameter to fulfill prosthetic requirements or for aesthetic reasons. Results:A total of 136 bone grafting procedures were performed. The mandibular external oblique line and ascending ramus were the most frequently used donor areas (59.64%) and block grafts (67.64%) were the most frequently used type of graft, frequently from the mandibular external oblique line/ascending ramus (52.18%). Platelet-rich plasma was used in 20.1% of all procedures, usually associated with particulate bone grafts. Maxillary procedures represented the majority of surgeries (75%), but with fewer complications compared with the mandible. Sinus mucosa perforation was the most frequent complication in maxillary procedures, whereas graft exposure was the most common complication in mandible. Conclusions:Alveolar reconstruction using autogenous bone followed by implant placement is a reliable treatment for patients with insufficient bone. Complications and morbidity were frequently observed. However, in only 6.6% of all procedures, the final rehabilitation with dental implants was not possible.

Intraosseous leiomyoma of the mandible

An intraosseous leiomyoma arising within the mandible was diagnosed in a 24-year-old woman. Clinically, a nodular swelling of the lower border of the mandible was noted. Radiographically, a unilocular ellipsoid radiolucency, loss of the lower border of the mandible, and tooth resorption were observed. The mitotic count was 0.4 per 10 high-power fields, which supported the benign nature of the tumor. The clinical and histologic parameters for distinguishing between benign and malignant smooth muscle neoplasms are discussed.

Plasma treatment maintains surface energy of the implant surface and enhances osseointegration

The surface energy of the implant surface has an impact on osseointegration. In this study, 2 surfaces: nonwashed resorbable blasting media (NWRBM; control) and Ar-based nonthermal plasma 30 days (Plasma 30 days; experimental), were investigated with a focus on the surface energy. The surface energy was characterized by the Owens-Wendt-Rabel-Kaelble method and the chemistry by X-ray photoelectron spectroscopy (XPS). Five adult beagle dogs received 8 implants (n = 2 per surface, per tibia). After 2 weeks, the animals were euthanized, and half of the implants (n = 20) were removal torqued and the other half were histologically processed (n = 20). The bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were evaluated on the histologic sections. The XPS analysis showed peaks of C, Ca, O, and P for the control and experimental surfaces. While no significant difference was observed for BIC parameter (P > 0.75), a higher level for torque (P < 0.02) and BAFO parameter (P < 0.01) was observed for the experimental group. The surface elemental chemistry was modified by the plasma and lasted for 30 days after treatment resulting in improved biomechanical fixation and bone formation at 2 weeks compared to the control group.

The effect of a nanothickness coating on rough titanium substrate in the osteogenic properties of human bone cells

This study evaluated the effect of a bioactive ceramic coating, in the nanothickness range, onto a moderately rough surface on the osteogenic behavior of human bone cells. The cells were harvested from the mandibular mental region and were cultured over Ti-6Al-4V disks of different surfaces: as-machined (M), alumina-blasted/acid etched (AB/AE), and alumina-blasted/acid-etched + 300-500 nm thickness amorphous Ca- and P-based coating obtained by ion beam-assisted deposition (Nano). The culture was then evaluated regarding cell viability, adhesion, morphology, immunolocalization of osteopontin (OPN) and alkaline phosphatase (ALP). The results showed that the surface treatment did not interfere with cell viability. At 1 day, AB/AE and Nano showed higher adhesion than the M surface (p < 0.001). Higher adhesion was observed for the M than the Nano surface at 7 days (p < 0.005). The percentage of cells showing intracellular labeling for OPN at day 1 was significantly higher for the Nano compared to M surface (p < 0.03). The percentage of ALP intracellular labeling at 7 days was significantly higher for the AB/AE compared to the M surface (p < 0.0065); no differences were detected at 14 days. Our results suggest that the presence of a thin bioactive ceramic coating on a rough substrate did not favor the events related to in vitro osteogenesis. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

Implant biomechanical stability variation at early implantation times in vivo: an experimental study in dogs.

PURPOSE To demonstrate the degree of stability decrease and subsequent increase of dental implants at early implantation times in a beagle model. MATERIALS AND METHODS The mandibular premolars and first molars of eight beagle dogs were extracted and the ridges allowed to heal for 8 weeks. Thirty-two (n = 16 each group) implants were placed bilaterally, and remained in vivo for 1 and 3 weeks. The implants with comparable dimensions were divided as follows: group 1, Straumann Bone Level with SLActive surface; group 2, Nobel Speedy Replace RP with TiUnite surface. During insertion and following sacrifice, the implants were torqued to determine insertion and interface failure values. Histologic sections were prepared for microscopy. Statistical analysis was performed using Kruskal-Wallis and multiple paired and non-paired t tests considering unequal variances at a 95% level of significance. RESULTS High insertion torque values were observed along with a significant decrease at 1 week in vivo (P = .003). At 3 weeks, the biomechanical fixation levels increased and were comparable to the insertion torque value. Histology showed that interfacial bone remodeling and initial woven bone formation was observed around both implant groups at 1 and 3 weeks. CONCLUSIONS As time elapsed early after implantation, the biomechanical stability of dental implants initially decreased and subsequently increased.

Saliva versus peri-implant inflammation: quantification of IL-1β in partially and totally edentulous patients.

The aim of this study was to investigate the potential use of salivary IL1β in early-stage diagnostics of peri-implant inflammation in partially and totally edentulous patients rehabilitated with dental implants. Patients were classified according to peri-implant probing depth and bleeding upon probing in groups of healthy individuals or in groups of individuals with peri-implant inflammation. Data on plaque index, clinical attachment loss, suppuration, and mobility were also assessed. Saliva was collected without stimulation, and the levels of IL-1β were determined by ELISA. Healthy groups demonstrated significantly lower levels of IL-1β compared with the inflammation groups. No difference in IL-1β levels was observed between partially edentulous or totally edentulous patients. Salivary IL-1β may be useful for the diagnosis and monitoring of early peri-implant inflammation, particularly in edentulous patients.

Three-dimensional evaluation of superior airway space after orthognathic surgery with counterclockwise rotation and advancement of the maxillomandibular complex in Class II patients

OBJECTIVE The aim of this study was to assess changes in the superior airway space (SAS) in Class II patients undergoing orthognathic surgery with counterclockwise rotation of the maxillomandibular complex (MMC). STUDY DESIGN A total of 23 patients (15 females and 8 males; mean age, 33 years) with symptoms of respiratory disease (mouth breathing) were studied. The patients were subjected to computed tomography analyses at two time intervals: T1 (preoperatively) and T2 (postoperative minimum of 6 months). The computed tomography images were exported to Dolphin Imaging 11.5 software to measure the surface area, minimum axial area, and volume of the SAS. RESULTS The surgery (including a median mandibular advancement of 14 mm with an average rotation of 8 degrees) significantly increased the static SAS, with mean postoperative increases of 178 mm(2) in SA, 76.67 mm(2) in minimum axial area, and 10118.5 mm(3) in volume. A significant increase was also observed in the three-dimensional airspace following orthognathic surgery, which provided a greater permeability of the SAS in Class II patients. CONCLUSIONS This confirmed the efficacy of this technique in the treatment of respiratory disorders.

Evaluation of the Bone Healing Process Utilizing Platelet-Rich Plasma Activated by Thrombin and Calcium Chloride: A Histologic Study in Rabbit Calvaria

To evaluate the bone healing of defects filled with particulate bone graft in combination with platelet-rich plasma (PRP), added with a mixture of calcium chloride and thrombin or just calcium chloride. Two 5-mm bone defects were created in the calvaria of 24 rabbits. Each defect was filled with particulate bone graft and PRP. In one defect the PRP was activated by a mixture of calcium chloride and thrombin; in the other, PRP was activated by calcium chloride only. The animals were euthanized 1, 2, 4, and 8 weeks after the surgeries, and the calvaria was submitted to histologic processing for histomorphometric analysis. The qualitative analysis has shown that both defects presented the same histologic characteristics so that a better organized, more mature, and well-vascularized bone tissue was noticed in the eighth week. A good bone repair was achieved using either the mixture of calcium chloride and thrombin or the calcium chloride alone as a restarting agent of the coagulation process.

Bovine Anorganic Bone Graft Associated with Platelet-Rich Plasma: Histologic Analysis in Rabbit Calvaria

Autogenous bone tissue has regeneration potential; however, this capacity may not be sufficient in larger bone defects. The aim of this study is to histologically evaluate anorganic bovine bone grafts (GenOx Inorg) with or without platelet-rich plasma (PRP). Two bone lesions were created in calvaria of 12 rabbits. The 24 surgical lesions were separated into 3 groups: coagulous, anorganic, and anorganic with PRP. At the 4-week time point, the animals were euthanized and the grafted area removed, fixed in formalin 10% with phosphate buffered saline, 0.1 M, and embedded in paraffin. The histologic parameters analyzed were new bone filling the defect area, presence of giant cells and particles of the graft, and new bone formation associated with the particles. In the coagulous group, defects were filled with fibrous tissue that attached the periosteum and little bone neoformation in the periphery. In anorganic groups with or without PRP, little new bone formation in the periphery of the defect was observed; however, in the center of some defects there was new bone. Moderate presence of giant cells and little new bone formation was associated with the innumerous graft particles. Histologic results revealed no statistically significant differences among the defects new bone fill between the studied groups (P = .64). There was no significant difference in the number of giant cells (P = .60), graft particles (P = .46), and new bone formation around graft particles (P = .26), whether PRP was added or not. Anorganic bone, isolated or mixed with PRP, was biocompatible and osteoconductive, while maintaining bone volume.