The influence of cone-beam computed tomography and periapical radiographic evaluation on the assessment of periapical bone destruction in dog`s teeth

Objective. The aim of this study was to determine the influence of periapical radiographs, cone beam computed tomography (CBCT) sections, and cone beam volumetric data on the determination of periapical bone destruction in endodontically treated distal root canals of premolar canine teeth. Nontreated mesial roots were used as controls. Study design. Enterococcus faecalis strain (ATCC 29212) was inoculated into 30 root canals of 2 mongrel dogs to induce apical periodontitis. After 60 days, the root canals of the distal roots of the 11 mandibular and 4 maxillary premolars were endodontically treated (n = 15). The mesial root canals were used as controls (no treatment). The bone destruction was evaluated after 6 months by 5 evaluators using periapical radiographs and by CBCT (coronal and sagittal sections). After the experimental period, the area of the lesions in periapical radiographs and CBCT sections were measured in mm(2) using the ImageTool software. A single evaluator measured the volumetric data using the OsiriX software. The comparison between the diagnosis methods in treated root canals and controls was performed using parametric and nonparametric criteria. The Pearson correlation coefficient was computed between radiographic values and CBCT volumetric data in treated root canals and controls. Results. The results showed the presence of chronic apical periodontitis in every inoculated tooth. After 6 months, periapical radiographs, coronal CBCT sections, and volumetric data showed lower bone destruction in endodontically treated teeth in comparison with the control group (P < .05). The 5 evaluators found no differences between the apical periodontitis area of treated teeth and controls when CBCT sagittal sections were used (P > .05). No correlation was found between x-ray and CBCT volumetric values in treated root canals. Conclusions. Although selected CBCT sagittal sections showed similar values of bone destruction in endodontically and nontreated root canals, volumetric CBCT data showed that periapical lesions of endodontically treated root canals had half of the volume of periapical lesions in nontreated root canals. No relationship could be found between the periapical values of bone destruction and volumetric data found in CBCT of treated rood canals. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011; 112: 272-279)

Bone crestal height and bone density after third-molar extraction and grafting: a long-term follow-up study

The objective of this study was to evaluate the long-term influence of xenogenic grafts on bone crestal height and radiographic density following extraction of teeth. The right and left third lower molars of 22 patients were surgically extracted, and one randomly chosen socket was filled with a xenogenic graft (Gent-Tech). The contralateral molar was left to heal naturally, serving as a paired control. Digital intraoral radiographies were taken at surgery and 2, 6, and 24 months after, to evaluate bone density (BD) and alveolar bone crest to cementoenamel junction distance. The data obtained were subjected to two-way analysis of variance and Tukey`s test (alpha = 0.05). The significant decrease in cementoenamel junction distance observed for both groups was limited to the first 6 months. BD values increased significantly in the first 6 months, with no alterations observed up to 24 months for both groups. BD was higher for the experimental group at all time points (p < 0.05). Socket grafting with the xenogenic materials tested did not changed bone crestal height and bone radiographic density in the long term.

Effect of Smoking on Early Bone Healing Around Oxidized Surfaces: A Prospective, Controlled Study in Human Jaws

Background: This prospective and controlled histologic study evaluates the impact of smoking on bone-to-implant contact, the bone density in the threaded area, and the bone density outside the threaded area around microimplants with anodized surface retrieved from human jaws. Methods: A total of 24 subjects (mean age 51.32 +/- 7.5 years) were divided in two groups: smokers (n = 13 subjects) and non-smokers (n = 11 subjects). Each subject received one microimplant with oxidized surface during conventional mandible or maxilla implant surgery. After 8 weeks, the microimplants and the surrounding tissue were removed and prepared for histomorphometric analysis. Results: Three microimplants placed in smokers showed no osseointegration. The newly formed bone showed early stages of maturation, mainly in the non-smokers. Marginal bone loss, gap, and fibrous tissue were present around implants retrieved from smokers. Histometric evaluation indicated that the mean bone-to-implant contact ranged between 25.97% +/- 9.02% and 40.01% +/- 12.98% for smokers and non-smokers, respectively (P <0.001). Smokers presented 28.17% +/- 10.32% of bone density in the threaded area, whereas non-smokers showed 46.34% +/- 19.12%. The mean of bone density outside the threaded area ranged between 18.76% and 25.11% for smokers and non-smokers, respectively (P>0.05). Conclusion: The present data obtained in human subjects confirm that smoking has a detrimental effect on early bone tissue response around oxidized implant surfaces. J Periodontol 2010;81:575-583.

Monostotic fibrous dysplasia: a 23-year follow-up of a patient with spontaneous bone remodeling

Fibrous dysplasia is a benign fibro-osseous disease that affects one or more bones. Although its etiology has been defined, the mechanism of spontaneous resolution is still unclear. There is strong evidence indicating the occurrence of stabilization when bone maturation is completed. Deformities that lead to esthetic and functional disorders are observed in almost all cases. Plastic surgery is often recommended when the maxilla and mandible are involved. In the case of mild deformities, careful follow-up during skeletal growth is recommended. We describe here the 23-year follow-up of a patient with monostotic fibrous dysplasia whose disease had stabilized by 13 years of follow-up. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107: 229-234)

Expression of bone resorption regulators (RANK, RANKL, and OPG) in odontogenic tumors

Objective. To investigate the expression of bone resorption regulators (receptor activator of nuclear factor kappa B [RANK], RANK ligand [RANKL], and osteoprotegerin [OPG]) in calcifying cystic odontogenic tumor (CCOT), adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor (CEOT), odontogenic myxoma (OM), and ameloblastic fibroma (AF). Study design. The expression of these mediators was evaluated by means of immunohistochemistry. Results. All specimens demonstrated positive immunoreactivity to RANK, RANKL, and OPG. The quantification of these mediators in epithelium revealed a similar pattern of expression for RANKL and OPG in CCOT, AOT, CEOT, and AF. With regard to stromal/mesenchymal cells, the majority of AOT and CCOT cases showed a higher content of OPG than RANKL, whereas CEOT, OM, and especially AF had a tendency to present a greater content of RANKL than OPG. Conclusion. Our data indicate that the CCOT, AOT, CEOT, OM, and AF cell constituents express key regulators of bone metabolism that might locally modulate tumor-associated bone resorption. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:548-55)

Expression of matrix metalloproteinases-2 and-9 and RECK during alveolar bone regeneration in rat

MMPs are endopeptidases that play a pivotal role in ECM turnover. RECK is a single membrane-anchored MMP-regulator. Here, we evaluated the temporal and spatial expression of MMP-2, MMP-9, and RECK during alveolar bone regeneration. The maxillary central incisor of Wistar rats was extracted and the animals were killed at 1, 3, 7, 10, 14, 21, 28, and 42 days post-operatively (n = 3/period). The hemimaxillae were collected, demineralized and embedded in paraffin. Immunohistochemical analysis was performed by the immunoperoxidase technique with polyclonal antibodies. On day 1, polymorphonuclear cells in the blood clot presented mild immunolabeling for MMPs. During bone remodeling, osteoblasts facing new bone showed positive staining for gelatinases and RECK in all experimental periods. MMPs were also found in the connective tissue and endothelial cells. Our results show for the first time that inactive and/or active forms of MMP-2, MMP-9 and RECK are differentially expressed by osteogenic and connective cells during several events of alveolar bone regeneration. This may be important for the replacement of the blood clot by connective tissue, and in the formation, maturation and remodeling of new bone.

Biomechanical and Microscopic Response of Bone to Titanium Implants in the Presence of Inorganic Grafts

This study evaluated the biomechanical and microscopic response of previously grafted bone to titanium implants. The lower incisors of 16 rabbits were surgically extracted, and bilateral perforations communicating with the remaining sockets were created distally. A socket/perforation defect on each mandible was chosen at random to be immediately filled with a xenogenic graft, whereas the contralateral perforation was left to heal naturally and served as a paired control. After 60 days, titanium implants were installed in the previously operated areas. After periods of 2 and 6 months, the animals were killed, and the force necessary to retrieve implants as well as the bone-implant contact (BIC) and bone mass (BM) were quantified and statistically compared by 2-way analysis of variance and Tukey`s test (alpha = .05). No significant differences in removal torque were observed, either by time or by treatment condition. Differences in BIC and BM between experimental and control groups were not statistically significant through the intervals studied (P < .05). The presence of a xenogenic graft did not influence the microscopic tissue response to titanium implants or fixation into newly formed or mature bone.

Histological and molecular temporomandibular joint analyses after mandibular advancement surgery: study in minipigs

Objectives. The objective of this study was to elucidate the changes occurring in the temporomandibular joint (TMJ) after surgical mandibular advancement with different fixation techniques: bicortical screws (rigid fixation) and miniplates (semi-rigid fixation). Study design. Eighteen minipigs were equally and randomly divided into 3 groups: Group I (control), nonoperated animals; Group II, animals submitted to surgical advancement surgery and osteosynthesis by bicortical screws; and Group III, animals submitted to surgical advancement surgery and osteosynthesis by miniplates. Four months after the surgeries, the presence of interleukin (IL)-6 and IL-10 in synovial fluid samples was assessed in ELISA experiments. TMJs were histologically prepared. Results. Higher levels of IL-10 (P = .0436) were found for Group II. Descriptive histological analysis was compatible with the ELISA findings. Conclusions. Rigid fixation evokes more pronounced signs of bone remodeling in the TMJ, whereas malleable fixation promotes a more intense inflammatory activity. Therefore, rigid fixation seems to transmit a higher impact of postoperative masticatory forces to the TMJ.

Two-dimensional radiographic and clinical references of the tooth crown for orthodontic mini-implant insertion: A guide-free technique

Objective. This study evaluated the reliability of tooth-crown radiographic references to aid in orthodontic mini-implant insertion and showed an insertion technique based on these references. Study design. The sample consisted of 213 interradicular septa evaluated in 53 bitewing radiographs. The proximal contour of adjacent tooth crowns was used to define septum width and its midpoint was linked to the interdental contact point to determine septum midline (SML). The distances from SML to mesial and distal teeth were measured and compared to evaluate SML centralization degree in 2 different septum heights. Results. The mesial and distal distances were not statistically different in the midpoint of the septum height, but they were different at the apical septum height. Conclusions. The tooth-crown radiographic references determine a high centralization degree of the SML on which an insertion site could be defined. The greater SML centralization degree was observed at the coronal septum area. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;110:e8-e16)

Growth hormone induces bone morphogenetic proteins and bone-related proteins in the developing rat periodontium

The hypothesis that growth hormone (GH) up-regulates the expression of enzymes, matrix proteins, and differentiation markers involved in mineralization of tooth and bone matrices was tested by the treatment of Lewis dwarf rats with GH over 5 days, The molar teeth and associated alveolar bone were processed for immunohistochemical demonstration of bone morphogenetic proteins 2 and 4 (BMP-2 and -4), bone morphogenetic protein type IA receptor (BMPR-IA), bone alkaline phosphatase (ALP), osteocalcin (OC), osteopontin (OPN), bone sialoprotein (BSP), and E11 protein (E11), The cementoblasts, osteoblasts, and periodontal ligament (PDL) cells responded to GH by expressing BMP-2 and -4, BMPR-IA, ALP, OC, and OPN and increasing the numbers of these cells. No changes were found in patterns of expression of the late differentiation markers BSP and E11 in response to GH, Thus, GH evokes expression of bone markers of early differentiation in cementoblasts, PDL cells, and osteoblasts of the periodontium. We propose that the induction of BMP-2 and -4 and their receptor by GH compliments the role of GH-induced insulin-like growth factor 1 (IGF-1) in promoting bone and tooth root formation.

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

Morphometric evaluation of the repair of critical-size defects using demineralized bovine bone and autogenous bone grafts in rat calvaria

Objective: To evaluate the repair of critical-size bone defects in rats treated with demineralized bovine bone (DBB) compared with autogenous bone (AB). Material and method: A bone defect of 8 mm in diameter was created in the calvaria of 50 Rattus norvegicus, treated either with DBB or AB. Sub-groups of five rats of each group were killed at 7, 14, 21, 30 and 90 days post-operatively, and the skulls were removed and processed histologically. Histological sections were stained with hematoxylin and eosin. Result: Histological analysis showed complete closure of the defects with new bone at 90 days in group AB, and substitution of the biomaterial by fibrotic connective tissue in the DBB group at 21 days. Morphometric analysis showed that DBB was rapidly absorbed at 14 days, with its volume density decreasing from 47%+/- 0.8% at 7 days to 1.2%+/- 0.41% at 14 days. Subsequently, volume densities of the connective tissue and neoformed bone increased from 51.1%+/- 11.17% to 86.8%+/- 7.92% and from 1.9%+/- 1.13% to 12%+/- 8.02%, respectively, for the same time interval. The volume density of AB particles did not change throughout the experimental periods, but the amount of new bone increased markedly between 7 and 90 days, from 4.5%+/- 1.57% to 53.5%+/- 6.42% (P < 0.05). Conclusion: DBB did not provide complete repair of the defects, with significantly less new bone formation than in the AB group.

COX-2 inhibition decreases VEGF expression and alveolar bone loss during the progression of experimental periodontitis in rats

Background: Vascular endothelial growth factor (VEGF) is a macromolecule of importance in inflammation that has been implicated in periodontitis. The aims of this study were to investigate VEGF expression during the progression of periodontal disease and to evaluate the effect of a preferential cyclooxygenase (COX)-2 inhibitor meloxicam on VEGF expression and alveolar bone loss in experimentally induced periodontitis. Methods: A total of 120 Wistar rats were randomly separated into groups 1 (control) and 2 (meloxicam, 3 mg/kg/day, intraperitoneally, for 3, 7, 14, or 30 days). Silk ligatures were placed at the gingival margin level of the lower right first molar of all rats. VEGF expression was assessed by reverse transcription-polymerase chain reaction (RT-PCR), Western blot (WB), and immunohistochemical (IHC) analyses. The hemiarcades were processed for histopathologic analysis. RT-PCR and WB results were submitted to analysis of variance, the Tukey test, and Pearson correlation analysis (P<0.05). Results: A reduction in alveolar bone resorption was observed in the meloxicam-treated group compared to the control group at all periods studied. There was a positive correlation between COX-2 mRNA and VEGF mRNA in the gingival tissues and periodontal disease (R = 0.80; P = 0.026). Meloxicam significantly reduced the increased mRNA VEGF expression in diseased tissues after 14 days of treatment (P = 0.023). Some alterations in VEGF receptor I mRNA expression were observed, but these were not statistically significant. VEGF protein expression in WB experiments was significantly higher in diseased sites compared to healthy sites (P<0.05). After 14 days of treatment with meloxicam, an important decrease in VEGF protein expression was detected in diseased tissues (P = 0.08). Qualitative IHC analysis revealed that VEGF protein expression was higher in diseased tissues and decreased in tissues from rats treated with meloxicam. Conclusions: The present data suggest an important role for VEGF in the progression of periodontal disease. Systemic therapy with meloxicam can modify the progression of experimentally induced periodontitis in rats by reducing VEGF expression and alveolar bone loss.

Osteointegration of Autogenous Bone Graft Associated With Osteoblastic Cells Under Treatment With Caffeine

Purpose: The present study investigated osteointegration of autogenous bone (AB) from calvaria graft associated with osteoblastic cells (OC) in bone defects in rats subjected to daily administration of caffeine. Materials and Methods: Male rats received daily intraperitoneal injection of 1.5% caffeine (0.2 mL/100 g body weight) or saline solution for 30 days. Then they were anesthetized, submitted to the extraction of the upper right incisor, and implanted with AB only and AB + OC. The animals were killed on 7th, 21st, and 42nd days after surgery, and their maxilla were processed for obtaining semiserial sections (5 mu m) stained with hematoxylin and eosin. Through image analysis system, the bone volume and the quality of graft in adjacent areas were estimated. Results: The results showed that in caffeine treatment, the AB + OC graft showed no foreign body and acute inflammatory reactions inside the defect when compared to AB. The histometric results revealed that the association AB + OC produced significant increase (10%-15%) in bone volume in later experimental period (42 days) when compared with saline solution group (P <= 0.01). Conclusions: It was concluded that the association of AB from calvaria + OC demonstrated progressive osteointegration and accelerated the repair of bone defects in animals treated with daily caffeine. (Implant Dent 2011;20:369-373)

Bone cell responses to the composite of Ricinus communis polyurethane and alkaline phosphatase

The aim of this study was to evaluate the response of osteoblastic cells to the composite of Ricinus cominunis polyurethane (RCP) and alkaline phosphatase (ALP) incubated in synthetic body fluid (SBF). RCP pure (RCPp) and RCP blended with ALP 6 mg/mL polymer (RCP+ALP) were incubated in SBF for 17 days. Four groups of RCP were tested: RCPp, RCP+ALP, and RCPp and RCP+ALP incubated in SBF (RCPp/SBF and RCP+ALP/SBF). Stem cells from rat bone marrow were cultured in conditions that allowed osteoblastic differentiation on RCP discs and were evaluated: cell adhesion, culture growth, cell viability, total protein content, ALP activity, and bone-like nodule formation. Data were compared by ANOVA or Kruskal-Wallis test. The group RCP-A P was highly cytotoxic and, therefore, was not considered here. Cell adhesion (p = 0.14), culture growth (p = 0.39), viability (p = 0.46) and total protein content (p = 0.12) were not affected by either RCP composition or incubation in SBE ALP activity was affected (p = 0.0001) as follows: RCPp < RCPp/SBF < RCP+ALP/SBF. Bone-like nodule formation was not observed on all evaluated groups. The composite RCP+ALP prior to SBF incubation is cytotoxic and must not be considered as biomaterial, but the incorporation of ALP to the RCP followed by SBF incubation could be a useful alternative to improve the biological properties of the RCP. (c) 2007 Wiley Periodicals, Inc.