Platelet-rich fibrin and collagen membrane in the preservation of the alveolar bone: Feasibility of the elemental inorganic composition and scanning electron microscopy analysis.

The success of dental implants is related to the amount, quality, and composition of the alveolar bone. The placement of platelet-rich fibrin (PRF) clot associated with a resorbable collagen membrane (RCM) in a postextraction alveolus is a technique used for ridge preservation. This case report study analyzed the ultrastructural characteristics of cross-sectioned alveolar bone that received PRF and RCM using scanning electron microscopy and the inorganic composition using "energy dispersive X-ray spectrometry," in order to explore the feasibility of this method to clinical studies. Three alveolar bone samples from two male patients (37 and 58 years old), obtained in the procedure of placing the dental implant, were analyzed. Two bone samples previously received PRF and RCM (M37 and M58), the third sample represented a physiological bone formation without treatment (M37-control). The bone sample M37 showed irregularly shaped islets of calcified material intermingled with connective tissue. The other samples, from the 58-year-old patient with PRF and RCM (M58); and the other untreated bone sample from the same 37-year-old patient (M37-control) showed similar ultrastructural morphology with trabecular conformation without islets agglomerations. The inorganic composition analysis showed higher concentrations of calcium and phosphorus in both samples treated with PRF and RCM in comparison to the untreated bone sample. The Ca/P ratio was higher in the M37 sample compared to the others samples. The results showed morphology and inorganic composition differences among the treatments used, suggesting that this method is feasible to analyze parameters of the alveolar bone tissue.

Zoledronic Acid Induces Site-Specific Structural Changes and Decreases Vascular Area in the Alveolar Bone.

PURPOSE: The aim was to assess the effect of a relevant regimen of zoledronic acid (ZA) treatment for the study of bisphosphonate-related osteonecrosis of the jaw on alveolar bone microstructure and vasculature. A sub-objective was to use 3-dimensional imaging to describe site-specific changes induced by ZA in the alveolar bone. MATERIALS AND METHODS: Five Wistar rats received ZA (0.6 mg/kg) and five (controls) received saline solution in the same volume. The compounds were administered intraperitoneally in 5 doses every 28 days. The rats were euthanized 150 days after therapy onset. The mandibles were scanned using high-resolution (14-µm) micro-computed tomography (micro-CT), decalcified, cut into slices for histologic analysis (5 µm), and stained with hematoxylin-eosin. Bone quality parameters were calculated using CT-Analyser software (Bruker, Kontich, Belgium) in 2 different volumes of interest (VOIs): the region between the first molar roots (VOI-1) and the periapical region under the first and second molars' apex (VOI-2). Blood vessel density and bone histomorphometric parameters were calculated only for the region between the roots of the first molar using AxioVision Imaging software (version 4.8; Carl Zeiss, Gottingen, Germany). RESULTS: ZA-treated rats showed a significant increase in percentage of bone volume and density (P < .05), with thicker and more connected trabeculae. Furthermore, the ZA group showed a significant decrease in the size of the marrow spaces and nutritive canals and in blood vessel density (P < .05). In the micro-CT evaluation, VOI-2 showed better outcomes in measuring the effect of ZA on alveolar bone. CONCLUSIONS: ZA treatment induced bone corticalization and decreased alveolar bone vascularization. VOI-2 should be preferred for micro-CT evaluation of the effect of bisphosphonates on alveolar bone. This analysis allowed the effect of ZA on alveolar bone and its vascularization to be characterized. The results of this analysis may add further knowledge to the understanding of the physiopathology of osteonecrosis of the jaw.

Alveolar bone remodeling after tooth extraction in irradiated mandible: An experimental study with canine model.

OBJECTIVES: The aim of the present study is to investigate the morphological and cellular changes in dental extraction socket that has been irradiated after the tooth extraction and to describe morphological characteristics of the osteocytes and osteocyte-lacunar-canalicular network (LCN) by scanning electron microscopy (SEM). MATERIAL AND METHODS: Five beagle dogs aged 1-2 years were used in this study. One side of each mandible was irradiated in two sessions and the other side of mandible (non-irradiated) served as a control. The mandible bone blocks were processed by bulk staining en bloc in basic fuchsin and the specimens were embedded routinely in polymethyl methacrylate resin without preliminary decalcification. All blocks were subjected to micro-CT imaging, after that the specimens were prepared for light microscopy and SEM. RESULTS: Alterations in bone macrostructure are minimal in irradiated bone, but the changes in LCN are clear. In the area of the tooth extraction socket, the connections of osteocytes to the vessels and to neighboring osteocytes were not observed both in irradiated and nonirradiated bone. However, osteoclasts were located in the bone surface entering inside to the bone between osteons. In the lamellar bone of lateral sides, a decrease in canalicular connections between osteocytes and periosteum was found in irradiated bone as compared to the non-irradiated side. CONCLUSIONS: The novelty of the present study is that radiation disrupts osteocytes and their dendrites.

Nanomechanical Assessment of Bone Surrounding Implants Loaded for 3 Years in a Canine Experimental Model.

PURPOSE: This work evaluated the nanomechanical properties of bone surrounding submerged and immediately loaded implants after 3 years in vivo. It was hypothesized that the nanomechanical properties of bone would markedly increase in immediately and functionally loaded implants compared with submerged implants. MATERIALS AND METHODS: The second, third, and fourth right premolars and the first molar of 10 adult Doberman dogs were extracted. After 6 months, 4 implants were placed in 1 side of the mandible. The mesial implant received a cover screw and remained unloaded. The remaining 3 implants received fixed dental prostheses within 48 hours after surgery that remained in occlusal function for 3 years. After sacrifice, the bone was prepared for histologic and nanoindentation analysis. Nanoindentation was carried out under wet conditions on bone areas within the plateaus. Indentations (n = 30 per histologic section) were performed with a maximum load of 300 µN (loading rate, 60 µN per second) followed by a holding and unloading time of 10 and 2 seconds, respectively. Elastic modulus (E) and hardness (H) were computed in giga-pascals. The amount of bone-to-implant contact (BIC) also was evaluated. RESULTS: The E and H values for cortical bone regions were higher than those for trabecular bone regardless of load condition, but this difference was not statistically significant (P > .05). The E and H values were higher for loaded implants than for submerged implants (P < .05) for cortical and trabecular bone. For the same load condition, the E and H values for cortical and trabecular bone were not statistically different (P > .05). The loaded and submerged implants presented BIC values (mean ± standard deviation) of 57.4 ± 12.1% and 62 ± 7.5%, respectively (P > .05). CONCLUSION: The E and H values of bone surrounding dental implants, measured by nanoindentation, were higher for immediately loaded than for submerged implants.

MEPE Localization in the Craniofacial Complex and Function in Tooth Dentin Formation.

Matrix extracellular phosphoglycoprotein (MEPE) is an extracellular matrix protein found in dental and skeletal tissues. Although information regarding the role of MEPE in bone and disorders of phosphate metabolism is emerging, the role of MEPE in dental tissues remains unclear. We performed RNA in situ hybridization and immunohistochemistry analyses to delineate the expression pattern of MEPE during embryonic and postnatal development in craniofacial mineralizing tissues. Mepe RNA expression was seen within teeth from cap through root formation in association with odontoblasts and cellular cementoblasts. More intense expression was seen in the alveolar bone within the osteoblasts and osteocytes. MEPE immunohistochemistry showed biphasic dentin staining in incisors and more intense staining in alveolar bone matrix and in forming cartilage. Analysis of Mepe null mouse molars showed overall mineralized tooth volume and density of enamel and dentin comparable with that of wild-type samples. However, Mepe(-/-) molars exhibited increased thickness of predentin, dentin, and enamel over controls and decreased gene expression of Enam, Bsp, Dmp1, Dspp, and Opnby RT-PCR. In vitro Mepe overexpression in odontoblasts led to significant reductions in Dspp reporter activity. These data suggest MEPE may be instrumental in craniofacial and dental matrix maturation, potentially functioning in the maintenance of non-mineralized matrix.

Test in canine extraction site preservations by using mineralized collagen plug with or without membrane.

The aim of this study was to discuss the feasibility of porous mineralized collagen plug and bilayer mineralized collagen-guided bone regeneration membrane in site preservation in extraction sockets. The third mandibular premolars on both sides were extracted from four dogs, thus there were 16 alveolar sockets in all dogs and were randomly assigned into three groups. Group A had six alveolar sockets, and groups B and C had five alveolar sockets, respectively. Each alveolar socket of group A was immediately implanted with a porous mineralized collagen plug and covered with a bilayer mineralized collagen-guided bone regeneration membrane after tooth extraction. Alveolar sockets of group B were implanted with porous mineralized collagen plug only, and group C was set as blank control without any implantation. The healing effects of the extraction sockets were evaluated by gross observation, morphological measurements, and X-ray micro-computed tomography after twelve weeks. Twelve weeks after operation, both groups A and B had more amount of new bone formation compared with group C; in terms of the degree of alveolar bone height, group A was lower than groups B and C with significant differences; the bone mineral density in the region of interest and bone remodeling degree in group A were higher than those of groups B and C. As a result, porous mineralized collagen plug could induce the regeneration of new bone in extraction socket, and combined use of porous mineralized collagen plug and bilayer mineralized collagen guided bone regeneration membrane could further reduce the absorption of alveolar ridge and preserve the socket site.

Alveolar bone loss induced by chronic ethanol consumption from adolescence to adulthood in Wistar rats.

Though there are literature indicating the bone loss due to alcohol consumption, studies on the association between ethanol consumption and periodontal breakdown in animals are either scarce or have provided conflicting results. Here, we investigated the effects of chronic alcohol exposure from adolescence to adulthood on the alveolar bone in rats. Wistar rats were exposed to ethanol (6.5 g/kg/day) in a solution of 22.5% (w/v) or distilled water (control) by gavage from 35 days of age (adolescent) until 90 days (adulthood). Evaluation of the bone loss was performed using scanning electronic microscopy, in which the distances between the cement-enamel junction and the alveolar bone crest from the palatal side of the first molar mandibular were measured. The measurements obtained were tabulated and analyzed using Student's t-test. Alcohol-treated group revealed greater bone loss in comparison to the control group. These findings indicate that heavy chronic alcohol exposure from adolescent to adulthood can induce alveolar bone loss in rats associated to absence of periodontitis.

Resin bonding to root dentin: influence of the alveolar bone level and thickness of the cement layer.

AIM: Aim of the present study was to evaluate the influence of the alveolar bone level and thickness of the cement layer on the push-out bond strength of fiber posts luted to root dentin. METHODS: We prepared post spaces in 60 bovine roots (16 mm), embedded in acrylic resin to simulate different scenarios of alveolar bone resorption. They were divided into six groups (N.=10), according to the factors "alveolar bone level" (14, 10, and 7 mm) and "cement thickness" (post no. 3/control and post no. 1/ thicker cement layer): G14P3 - 14-mm root + post n. 3; G10P3 - 10-mm root + post n. 3; G7P3 - 7-mm root + post n. 3; G14P1 - 14-mm root + post n. 1; G10P1 - 10-mm root + post n. 1; and G7P1 - 7-mm root + post n. 1. The fiber posts (White Post DC, FGM) were luted, and composite cores were made. Each specimen was subjected to mechanical cycling, and four slices were obtained from each root specimen and subjected to push-out testing in a universal testing machine. The data (MPa) were analyzed by ANOVA (two way) and Tukey's test (5%). RESULTS: The factor "cement thickness" (P=0.0057) significantly influenced bond strength, but the factor "alveolar bone level" (P=0.0605) did not. The thicker cement layer/post n. 3 presented bond strength values higher than those with cement layer/post n. 1. CONCLUSION: Bond strength was not influenced by different scenarios of alveolar bone resorption, although higher bond strength values were found for thinner cement layers.

Ultrastructural and immunohistochemical study of the effect of sodium alendronate in the progression of experimental periodontitis in rats.

The aim of the present research was to investigate the ultrastructural aspects and the immunoexpression of receptor activator of NFκB ligand (RANKL) and osteoprotegerin (OPG) on experimental periodontal disease of alendronate (ALN)-treated rats. Male Wistar rats received daily injections of 2.5 mg/kg body weight of ALN during 7 days previously and 7, 14, and 21 days after the insertion of a 4.0 silk suture into the gingival sulcus around the right upper second molar. Specimens were fixed in 0.1% glutaraldehyde + 4% formaldehyde under microwave irradiation, decalcified in 4.13% EDTA and paraffin embedded for TRAP histochemistry and immunohistochemistry for RANKL and OPG, or embedded in Spurr epoxy resin for TEM analysis. ALN reduced the activity of osteoclasts and significantly decreased the resorption of the alveolar crest. In the control group the alveolar crest appeared resorbed by TRAP-positive osteoclasts, which presented ultrastructural features of activated cells. The immunoexpression of RANKL was not inhibited by the drug; however, the expression of OPG was increased in the treated animals. The alveolar crest of ALN-treated specimens at 21 days showed signs of osteonecrosis, like empty osteocyte lacunae, the exposed bone regions and bacterial infection. The results showed that ALN treatment in individuals with periodontal disease represents a risk of osteonecrosis because of the reduced activity of osteoclasts resultant of the increased immunoexpression of OPG.

[Harmonic imaging analysis for assessment of morphological changes in mini-pig alveolar bone by normal and increased functional load].

The aim of the study was to reveal the mastication forces effect on the microstructure of mandible bone tissue of mini-pigs by Fouirier harmonic imaging analysis of bone sections images of back scattered electrons and assessment of calcium and phosphorous distribution maps obtained by roentgenofluorescence technique. The results showed that by higher functional loads not only the total content of mineral elements in the bone matrix increased but also the of the low-frequency harmonics in the image spectrum indicating structural heterogeneity decrease in bone mineralization.

Biological aspects of periodontal tissue regeneration: cementogenesis and the induction of Sharpey's fibres.

The realm of periodontal tissue regeneration has a plethora of unanswered questions and challenges due to the complexity of restoring mineralised and fibrous connective tissues ultimately to be covered by epithelium in a very specific spatial organisation. Wound healing of the periodontium follows a highly ordered sequence of events that guides cellular morphology, differentiation, migration and proliferation and comprises a series of cellular, extracellular and molecular reciprocal interactions. The prerequisite for regeneration of any structure is the trio of a soluble molecular signal, a scaffold and responding stem cells. Striated muscle represents an abundant source of easily accessible tissue that contains several perivascular, pericytic and myoblastic cell niches capable of differentiating and inducing selected tissue phenotypes and morphogenesis. Morcellated autogenous rectus abdominis muscle combined with 75 microg of hTGF-beta3 in Matrigel matrix implanted into non-human primate class II and III furcation defects induced greater alveolar bone formation and cementogenesis when compared to furcation defects without the addition of morcellated autogenous bone. In situ hybr disation and immunohistochemistry during embryonic development and tooth morphogenesis have shown synchronous but spatially different bone morphogenetic proteins (BMPs) expression during tissue induction and morphogenesis. Preclin cal studies in the non-human primate Papio ursinus have shown a seemingly specific cementogenic function of osteogenic protein-1 (OP-1, also known as BMP-7) when treating Class II furcation defects of Papio ursinus. In context, hOP-1 is preferentially cementogenic when implanted into non-human primate class II and III furcation defects whilst hBMP-2 is highly osteogenic but not cementogenic when in contact with dentine extracellular matrix. Importantly, naturally-derived highly purified BMPs/OPs, recombinant hOP-1 and hTGF-beta3 when implanted into non-human primates Class II and III furcation defects induce cementogenesis with morphologically and functionally oriented periodontal ligament fibres coursing within a newly formed highly vascular periodontal ligament space with Sharpey's fibres generated within the newly secreted cementoid matrix. The grand challenge of molecular and therapeutic implications is the biological significance of apparent redundancy. The presence of several homologous but molecularly different isoforms all endowed with the striking capacity of inducing "bone formation by autoinduction" indicates that there is a structure/activity profile amongst soluble osteogenic molecular signals; this suggests a therapeutic significance in clinical contexts. The structure/activity profile finely tunes the vast pleiotropic activities of the soluble molecular signals in mineralised and non-mineralised tissues profoundly modulating epithelial/mesenchymal tissue interactions. Significant advances in regenerative tissue engineering may be expected if ongoing research is tailored to provide further mechanistic and morphological insights into the relevance of the apparent redundancy and the structure/activity profile of the recombinant human osteogenic proteins. The presence of the structure/activity profile together with the biological significance of apparent redundancy will necessitate re-shaping and re-engineering developing newly devised targeted therapeutics for periodontal tissue engineering.

Periodontal microstructure change and tooth movement pattern under different force magnitudes in ovariectomized rats: an in-vivo microcomputed tomography study.

INTRODUCTION: The purpose of this study was to evaluate the dynamic changes in the periodontal microstructure and the molar displacement pattern during orthodontic tooth movement in ovariectomized rats. METHODS: Twenty ovariectomized rats received either 100 or 30 g of orthodontic force to induce mesial movement of the maxillary left first molars over 14 days. Ten healthy rats underwent sham operations as controls. Periodontal ligament thickness, alveolar bone microstructural properties, and displacement of the molar were measured with 6 in-vivo microcomputed tomography scans for each sample. RESULTS: The ovariectomized rats that received 100 g of orthodontic force had obvious changes in periodontal ligament thickness at day 1 and poor periodontal ligament thickness recovery from days 5 through 14. The bone volume fraction increased and the trabecular separation decreased significantly in this group at day 3, and obvious bone loss was observed at day 14. Molar linear and angular movements were also higher in this group than in the other 2 groups. CONCLUSIONS: Relatively heavier force applications in ovariectomized rats resulted in poor periodontal ligament thickness recovery and local alveolar bone overcompression, and consequently induced undermining resorption and obvious alveolar bone loss; these led to high rates of tooth movement and molar inclination.

Miniscrew design and bone response: defining a correlation.

AIM: This prospective clinical trial aims at correlating miniscrew implant (MSI) micro/macro architecture, the method of placement, and biologic markers in peri-MSI crevicular fluid (PMICF) as indicators of bone response. A comparative evaluation of surface morphology of the MSIs before placement and after retrieval defines a correlation between the architecture of the MSIs and the bone- implant contact ratio. METHODS: Two types of MSIs (hybrid and cylindric) were placed in ten patients using a split-mouth technique with the aid of a restricted random number table. Each of the MSIs was placed in the intraradicular area between the second premolar and first molar in the attached gingiva, 4 mm from the cementoenamel junction. The MSIs were immediately loaded, and PMICF was collected on days 0, 7, 14, 21, 28, and 42 and evaluated using a standard laboratory protocol. Surface morphology before placement and after retrieval of the MSI was observed using scanning electron microscopy (SEM) at a magnification of ×11, ×40, and ×1,000. RESULTS: Alkaline phosphatase (ALP) and aspartate aminotransferase (AST) levels observed were lower in the hybrid MSI in comparison to the cylindric MSI. For both MSIs, ALP and AST levels showed a trend of significant increase at days 0, 7, and 14 and then a significant decrease on days 21, 28, and 42. Observations from SEM showed an oxide layer over the entire surface of the bone-expanding hybrid MSI; this layer was observed only at the tip of the cylindric MSI. CONCLUSIONS: Levels of both the diagnostic tissue destruction biologic markers ALP and AST are significantly higher in cylindric MSIs compared with hybrid MSIs, indicating a correlation to the type and method of placement of the MSI. The inflammatory markers show a definitive trend, with an elevation until day 14 and a decline after that, indicating an active inflammatory process until day 14 that could be correlated to tissue trauma. Observations from the SEM show a greater oxide layer formation in the hybrid MSI, which could imply a better bone-MSI contact ratio.

Particulate bone matrix usage for alveolar bone conservation. A histomorphometric study.

UNLABELLED: Different filling materials have been used in an attempt to repair bone loss situations. OBJECTIVE: The present study aimed to examine the effect of a bone matrix in post - extraction remodelling of the alveolar bone, and to perform a histomorphometric analysis of the residual alveolar ridges in Wistar rats. MATERIAL AND METHODS: Both rat first lower molars were extracted and the right alveoli were filled with particles of a bone matrix with mineral components (MO - UNC) (experimental group, EG). The left alveoli were used as a control group (CG). The animals were sacrificed at 0 hr., 15, 30 and 60 days after extraction, and the samples were processed. Histological sections were made at the level of the mesial alveolus of the first lower molar. Repair of the alveoli was histologically evaluated and a histomorphometric study of total alveolar volume (TAV), height of the buccal plate (Bh), height of the lingual plate (Lh) and percentage of osseointegration (OI) of the particles was performed to compare the residual ridges of CG with those of the EG. Statistical analysis of the data was performed. RESULTS: In the cases of the experimental group, newly - formed bone tissue was identified around the MO - UNC particles (osseointegration). Histomorphometric data indicate that, at 60 days post - extraction, TAV was significantly greater for EG when compared with CG (p <0.05) and the percentage of osseointegration of the particles increased as a function of time (57.6 %, 90.5% y 95.5%, for EG at 15, 30 y 60 days respectively). CONCLUSIONS: The bone matrix (MO - UNC) evaluated in this study is an osteoconductive material that prevents the collapse of post - extraction alveolar bone.

Is micro-computed tomography reliable to determine the microstructure of the maxillary alveolar bone?

OBJECTIVES: To analyze the reliability of micro-computed tomography (micro-CT) to assess bone density and the microstructure of the maxillary bones at the alveolar process in human clinics by direct comparison with conventional stereologic-based histomorphometry. MATERIALS AND METHODS: Analysis of osseous microstructural variables including bone volumetric density (BV/TV) of 39 biopsies from the maxillary alveolar bone was performed by micro-CT. Conventional stereologic-based histomorphometry of 10 bone biopsies was performed by optic microscopy (OM) and low-vacuum surface electronic microscopy (SEM). Percentages of bone between micro-CT and conventional stereologic-based histomorphometry were compared. RESULTS: Significant positive correlations were observed between BV/TV and the percentage of bone (%Bone) analyzed by SEM (r = 0.933, P < 0.001), by toluidine blue staining OM (r = 0.950, P < 0.001) and by dark field OM (r = 0.667, P = 0.05). The high positive correlation coefficient between BV/TV and trabecular thickness illustrates that a value of BV/TV upper than 50% squares with a bone presenting most of their trabecules thicker than 0.2 mm. The high negative correlation between BV/TV and trabecular separation shows that values of BV/TV upper than 50% squares with a bone presenting most of their trabecules separated less than 0.3 mm each other. CONCLUSION: BV/TV assessed by micro-CT correlates with the percentage of bone assessed by conventional stereologic-based histomorphometry. Micro-CT is a reliable technique to determine the bone density and the microstructure of the maxillary alveolar bone at the site of dental implant insertion.

Correlations between alveolar bone microstructure and bone turnover markers in pre- and post-menopausal women.

OBJECTIVE: Alveolar cancellous bone biopsy samples were extracted during dental implant preparation for investigating microstructural changes due to menopause and relationships between these changes and bone turnover markers. STUDY DESIGN: Subjects were 18 women receiving mandibular implants: premenopausal (n = 5), early postmenopausal (≤5 years; n = 3), and late postmenopausal (>5 years; n = 10). Bone turnover markers were measured and the samples analyzed using microscopic computerized tomography and 3-dimensional bone morphometry. RESULTS: The alveolar bone volume was significantly less in late postmenopausal women than in premenopausal ones. The trabeculae in early postmenopausal women were more separated and rod-like than in premenopausal ones (P < .05). Each alveolar bone parameter was significantly (P < .05) related to at least 1 bone turnover marker. CONCLUSIONS: Alveolar cancellous bone structure begins changing even in early postmenopausal women, and this structure varies in close relationship to bone turnover markers.

In vivo microcomputed tomography evaluation of rat alveolar bone and root resorption during orthodontic tooth movement.

OBJECTIVE: To observe the real-time microarchitecture changes of the alveolar bone and root resorption during orthodontic treatment. MATERIALS AND METHODS: A 10 g force was delivered to move the maxillary left first molars mesially in twenty 10-week-old rats for 14 days. The first molar and adjacent alveolar bone were scanned using in vivo microcomputed tomography at the following time points: days 0, 3, 7, and 14. Microarchitecture parameters, including bone volume fraction, structure model index, trabecular thickness, trabecular number, and trabecular separation of alveolar bone, were measured on the compression and tension side. The total root volume was measured, and the resorption crater volume at each time point was calculated. Univariate repeated measures analysis of variance with Bonferroni corrections were performed to compare the differences in each parameter between time points with significance level at P < .05. RESULTS: From day 3 to day 7, bone volume fraction, structure model index, trabecular thickness, and trabecular separation decreased significantly on the compression side, but the same parameters increased significantly on the tension side from day 7 to day 14. Root resorption volume of the mesial root increased significantly on day 7 of orthodontic loading. CONCLUSIONS: Real-time root and bone resorption during orthodontic movement can be observed in 3 dimensions using in vivo micro-CT. Alveolar bone resorption and root resorption were observed mostly in the apical third on day 7 on the compression side; bone formation was observed on day 14 on the tension side during orthodontic tooth movement.

Particulate bone matrix usage for alveolar bone conservation. A histomorphometric study / Particulate bone matrix usage for alveolar bone conservation. A histomorphometric study.

UNLABELLED: Different filling materials have been used in an attempt to repair bone loss situations. OBJECTIVE: The present study aimed to examine the effect of a bone matrix in post - extraction remodelling of the alveolar bone, and to perform a histomorphometric analysis of the residual alveolar ridges in Wistar rats. MATERIAL AND METHODS: Both rat first lower molars were extracted and the right alveoli were filled with particles of a bone matrix with mineral components (MO - UNC) (experimental group, EG). The left alveoli were used as a control group (CG). The animals were sacrificed at 0 hr., 15, 30 and 60 days after extraction, and the samples were processed. Histological sections were made at the level of the mesial alveolus of the first lower molar. Repair of the alveoli was histologically evaluated and a histomorphometric study of total alveolar volume (TAV), height of the buccal plate (Bh), height of the lingual plate (Lh) and percentage of osseointegration (OI) of the particles was performed to compare the residual ridges of CG with those of the EG. Statistical analysis of the data was performed. RESULTS: In the cases of the experimental group, newly - formed bone tissue was identified around the MO - UNC particles (osseointegration). Histomorphometric data indicate that, at 60 days post - extraction, TAV was significantly greater for EG when compared with CG (p <0.05) and the percentage of osseointegration of the particles increased as a function of time (57.6

, for EG at 15, 30 y 60 days respectively). CONCLUSIONS: The bone matrix (MO - UNC) evaluated in this study is an osteoconductive material that prevents the collapse of post - extraction alveolar bone.

Particulate bone matrix usage for alveolar bone conservation. A histomorphometric study. / Particulate bone matrix usage for alveolar bone conservation. A histomorphometric study.

UNLABELLED: Different filling materials have been used in an attempt to repair bone loss situations. OBJECTIVE: The present study aimed to examine the effect of a bone matrix in post - extraction remodelling of the alveolar bone, and to perform a histomorphometric analysis of the residual alveolar ridges in Wistar rats. MATERIAL AND METHODS: Both rat first lower molars were extracted and the right alveoli were filled with particles of a bone matrix with mineral components (MO - UNC) (experimental group, EG). The left alveoli were used as a control group (CG). The animals were sacrificed at 0 hr., 15, 30 and 60 days after extraction, and the samples were processed. Histological sections were made at the level of the mesial alveolus of the first lower molar. Repair of the alveoli was histologically evaluated and a histomorphometric study of total alveolar volume (TAV), height of the buccal plate (Bh), height of the lingual plate (Lh) and percentage of osseointegration (OI) of the particles was performed to compare the residual ridges of CG with those of the EG. Statistical analysis of the data was performed. RESULTS: In the cases of the experimental group, newly - formed bone tissue was identified around the MO - UNC particles (osseointegration). Histomorphometric data indicate that, at 60 days post - extraction, TAV was significantly greater for EG when compared with CG (p <0.05) and the percentage of osseointegration of the particles increased as a function of time (57.6

, 90.5

y 95.5

, for EG at 15, 30 y 60 days respectively). CONCLUSIONS: The bone matrix (MO - UNC) evaluated in this study is an osteoconductive material that prevents the collapse of post - extraction alveolar bone.

The effect of covering materials with an open wound in alveolar ridge augmentation using beta-tricalcium phosphate: an experimental study in the dog.

PURPOSE: This study aimed to examine the effectiveness of a grafting technique using beta-tricalcium phosphate (Β-TCP) covered with different materials in alveolar bone defects with dehiscences. MATERIALS AND METHODS: In five beagle dogs, all premolars in the mandible were extracted bilaterally. After a 12-week healing period, two bone defects (length, 5 mm; width, 5 mm; depth, 7 mm) were created on each side of the mandible, and the buccal bone plate was resected. The four bone defects were randomly assigned to one of the following treatments: group 1, Β-TCP alone (TCP group); group 2, Β-TCP graft covered with collagen sponge (TCP+collagen group); group 3, Β-TCP graft covered with free buccal mucosa (TCP+mucosa group); group 4, no treatment (control group). The microarchitecture of the regenerated bone was observed using microcomputed tomography, and the area of newly formed bone was measured. Specimens from each defect were selected and subjected to histologic and histomorphometric analysis; areas of newly formed bone and the ridge width were measured in the specimens. RESULTS: Significant differences were found between the control group and all test groups. The median horizontal width of the ridge 2 mm from the top of the alveolar crest in the TCP+mucosa group was significantly greater than that of the TCP group. There was no significant difference between the TCP+mucosa and TCP+collagen groups in any measurement. CONCLUSIONS: Application of Β-TCP grafts to alveolar bone defects with dehiscence and covering of the open wound with free buccal mucosa or collagen sponge may be useful for ridge augmentation. Compared to no treatment or leaving the wound uncovered, these approaches resulted in more new bone formation and provided adequate horizontal mandibular width.