Bone Regeneration Using Bone Morphogenetic Protein-2 and Biphasic Calcium Phosphate With and Without Collagen Membrane in Calvarial Standardized Defects: An In Vivo Microcomputed Tomographic Experiment in Rats

The aim of this in vivo microcomputed tomographic (μCT) experiment was to assess in real time the efficacy of a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) and biphasic calcium phosphate (BCP), with and without resorbable collagen membrane (CM), in regeneration of standardized calvarial defects (SCDs) in rats. A total of 30 female Wistar albino rats (n = 10/group) with a mean age and weight of 7.5 months and 275 g, respectively, were used. With the rats under general anesthesia, the calvaria were exposed using full-thickness periosteal flaps and unilateral SCDs of 4.6 mm diameter were created on the left parietal bone. Defects were left untreated (control group) or randomly filled with either BCP soaked in rhBMP-2 and then covered with CM (BMP + BCP + CM group) or BCP soaked in rhBMP-2 alone (BMP + BCP group). In vivo μCT scans were done at baseline and 2, 4, 6, and 8 weeks. Newly formed bone (NFB) and remaining BCP particles were assessed for their volumes (NFBV, BCPV, respectively) and mineral densities (NFBMD, BCPMD, respectively). In vivo μCT results showed scanty amounts of new bone at the peripheries of the defect in the control group. In the other two groups, near complete defect closure was evident at 8 weeks. The mean NFBV after 8 weeks was 4.63 ± 0.96 mm(3), 11.82 ± 1.17 mm(3), and 13.85 ± 1.89 mm(3) for the control, BMP + BCP + CM, and BMP + BCP groups, respectively. After 8 weeks, the mean NFBMD was 0.38 ± 0.03 g/mm(3), 0.24 ± 0.07 g/mm(3), and 0.35 ± 0.03 g/mm(3) for the control, BMP + BCP + CM, and BMP + BCP groups, respectively. After 8 weeks, the mean BCPV and BCPMD values for the BMP + BCP + CM and BMP + BCP groups were 2.73 ± 0.65 mm(3), 0.33 ± 0.08 g/mm(3), 2.49 ± 0.71 mm(3), and 0.28 ± 0.03 g/mm(3), respectively. The present real-time in vivo μCT experiment demonstrated that BMP + BCP, either with or without CM, was effective in promoting bone regeneration within rat SCDs and enabled new bone formation starting as early as 2 weeks.

Guided Bone Regeneration Using Biphasic Calcium Phosphate With Adjunct Recombinant Human Bone Morphogenetic Protein-2 With and Without Collagen Membrane in Standardized Calvarial Defects in Rats: A Histologic and Biomechanical Analysis

This study aimed to assess the efficacy of biphasic calcium phosphate (BCP) with adjunct recombinant human bone morphogenetic protein-2 (rhBMP-2), with and without collagen membrane (CM), in regeneration of standardized rat calvarial defects. Thirty female Wistar albino rats with a mean age of 12 weeks and mean weight of 300 g were used. The skin over the calvaria was exposed using a full-thickness flap. A standardized defect measuring 4.6 mm in diameter was created in the parietal bone. The defects were randomly divided into the following groups: (1) no treatment (control group); (2) BCP soaked in rhBMP-2 and then covered with a resorbable CM; and (3) BCP soaked in rhBMP-2. Following euthanasia, histologic, histomorphometric, and biomechanical assessments of the calvarial specimens were performed to assess bone regeneration. The results showed islands of newly formed bone (NFB) between the defect edges in the control group. NFB was observed bridging the defect edges and around the remnants of BCP in the rhBMP-2 + BCP + CM group and only around the BCP remnants in the rhBMP-2 + BCP group. Histomorphometric analysis revealed a significantly higher mean ± standard deviation (SD) percentage of NFB per defect in the rhBMP-2 + BCP + CM group (46.12 ± 2.56) compared with the control (11.79 ± 0.75) and rhBMP-2 + BCP (26.65 ± 1.48) groups. Although no differences were found in the hardness and elastic modulus (EM) of NFB between the rhBMP-2 + BCP + CM (hardness: 687.78 ± 4.74 MPa; EM: 27.71 ± 0.063 GPa) and the rhBMP-2 + BCP (hardness: 637.65 ± 6.32 MPa; EM: 21.49 ± 0.095 GPa) groups, the biomechanical parameters of NFB in the control group (hardness: 286.17 ± 9.49 MPa; EM: 12.62 ± 0.048 GPa) were significantly less. The experiment demonstrated the efficiency of rhBMP-2 + BCP in GBR, wherein the presence of CM leads to a greater percentage of new bone formation within standardized calvarial defects.

Orthodontic elastic band-induced periodontitis - A case report

Periodontal problems due to the use of elastic bands have been documented in the past. A 9-year-old girl reported to a periodontist with complaints of bleeding from gums and tooth mobility of upper right central incisor. This case, reports the early diagnosis and treatment of an acute localized periodontitis arising from the incorrect use of orthodontic elastic rubber bands to close a maxillary midline diastema. The elastic band induced periodontitis was treated with a combination of surgery, splinting, antibiotics and orthodontics. Removal of the etiologic agent improved the condition of the tooth.

Hemin-dependent modulation of the lipid A structure of Porphyromonas gingivalis lipopolysaccharide

Porphyromonas gingivalis is a periopathogen strongly associated with the development of adult-type periodontitis. Both the virulence characteristics of periopathogens and host-related factors are believed to contribute to periodontitis. P. gingivalis lipopolysaccharide (LPS) displays a significant amount of lipid A structural heterogeneity, containing both penta- and tetra-acylated lipid A structures. However, little is known concerning how the lipid A structural content of P. gingivalis is regulated. Alterations in the lipid A content may facilitate the ability of P. gingivalis to modulate the innate host response to this bacterium. In this report, it is shown that the concentration of hemin in the growth medium significantly modulates the lipopolysaccharide lipid A structural content of P. gingivalis. Hemin is a key microenvironmental component of gingival cervicular fluid which is believed to vary depending upon the state of vascular ulceration. At low hemin concentrations, one major penta-acylated lipid A structure was found, whereas at high concentrations of hemin, multiple tetra- and penta-acylated lipid A structures were observed. Hemin concentrations, not iron acquisition, were responsible for the alterations in the lipid A structural content. The modifications of the lipid A structural content were independent of the LPS extraction procedure and occurred in a variety of laboratory strains as well as a freshly obtained clinical isolate. The known hemin binding proteins Kgp and HmuR contributed to the lipid A modulation sensing mechanism. To the best of our knowledge, this is the first report that hemin, a clinically relevant microenvironmental component for P. gingivalis, can modulate the lipid A structure found in a bacterium. Since tetra- and penta-acylated P. gingivalis lipid A structures have opposing effects on Toll-like receptor 4 activation, the alteration of the lipid A structural content may have significant effects on the host response to this bacterium.