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PR 26 Mononuclear cell recruitment and development of lesions of endodontic origin
304 • Journal of Endodontics
PRIP231 H u m a n pulpal or gingival fibroblasts attached to polyglycolic acid scaffolds survive and function in vivo. B Buurma*, K Gu, D Mooney, B Rutherford. The University of Michigan Autologous tissue grafting for the restoration of oral tissues is limited by several factors including the availability of sufficient donor tissue. One solution to this problem may be to develop substitute tissue grafts by attaching cultured autologous cells to scaffolds comprised of natural or synthetic polymers, developing the cell/scaffold contructs in vitro, and implanting them into a suitable site in vivo. We have shown that human dental pulp and gingival fibroblasts attach to nonwoven poly(glycolic acid) scaffolds, divide, and express genes thought to be associated with dentinogenesis (i.e. BMP-2, -4, OP-1, MSX-2, ActRI, B M P R - I A , -IB, -II, and type I collagen) in vitro. However, successful implantation had not been demonstrated. After 48 h in vitro, c e l l / s c a f f o l d constructs were implanted subdermally into immunodeficient mice. Histological examination of cell/scaffold constructs after three weeks in vivo revealed blood vessels distributed throughout. Cell/scaffold constructs contained mRNA for the human-specific Alu D N A sequence, human S-14 ribosomal protein, and all of the genes listed above. Human cells, immunopositive for human type I collagen and human prolyl 4-hydroxylase, were sparsely distributed throughout the cell/scaffold construct. Th~se data reveal that HPF and HGF attached to PGA scaff01~ pnd imolanted in vivo survive and exvress some markers of ¢gnnective tissue formation.
P~I 2_Y_l
An in vitro evaluation of five materials as chamber floor sealants in endodontically treated teeth. B.K. Elliott, A.K. Mickel, S.M.A. Chogle*
Case Western Reserve University Five restorative materials were evaluated for their ability to seal the chamber floor of endodontically treated teeth: amalgam with cavity varnish, Geristore ®,Geristore ®bonded with Tenure ~, Tetric Flow®bonded with Syntac®/Heliobond ®, and Syntac®/Heliobond ® alone. The root canal system of eighty-seven molars were cleaned, shaped, and obt,urated. The pulp chambers of the teeth were then filled with methylene blue dye under vacuum conditions and subsequently embedded in orthodontic resin. The apical extent of dye penetration was evaluated by incremental grinding of the teeth in an apical to coronal direction until dye was visualized under 2.5X magnification. The results indicated that the performance of dentin-bonded composites was more effective (P<0.001) in the prevention of dye penetration than either unbonded Geristore~ and especially amalgam with cavity varnish. Dentin-bonded flowable composite resins were effective in preventing the penetration of methylene blue dye. The elimination of coronal microleakage in endodonticallv treated teeth may improve the prognosis of root canal therapy. The use of a flowable composite with a dentin bonding agent as a chamber floor sealant allows visualization of the coronal gutta-percha, is able to seal cotton placed in a post preparation, is quick and simple to use, and will not interfere with the aims of the restorative dentist.
Vol. 25, No. 4, April 1999
P.%~] Growth inhibition of Streptococcus milleri and 223 Staphylococcus aureus in human serum and dental pulp after single oral dose of clindamycin hydrochioride. P.E. Scott, A.K. Mickel, E. Choi* Case Western Reserve University The purpose of this study was to determine if, when, and for how long, a single close of oral administered clindamycin hydrochloride would reach therapeutic concentration levels in the tooth and pulp and in the serum. 15 human subjects were studied. Each had a bicuspid or molar to be extracted. 12 subjects received a single, 150 mg oral dose of clindamycin hydrochloride at time intervals that varied from 45, 90, 135 and 180 minutes preextraction. Three subjects served as negative controls and received no drug prior to extraction. Following extraction, the tooth pulp and serum were sampled. An agar diffusion method was utilized which measured zones of inhibition to bacterial growth. S. milleri and S. aureus were used as test organisms. The mean peak concentration occurred at 90 minutes and was maintained at peak levels through 135 minutes. The ratio of pulp to serum concentration varied only slightly when Streptococcus and Staphylococcus were used as the test microbes: the ratio was 0.45:1 for S. milleri and 0.43:1 for S. aureus. The results of this study indicate that a therapeutic level of clindamycin hydrochloride was attained following a single oral dose of 150 my. Given the rapidity with which this occurred, administration of leading doses of clindamycin might be unnecessary in the treatment of pulp infections caused by susceptible microorganisms.
P~[ 2ZJ
M o n o n u c l e a r cell recruitment and development of lesions of endodontic origin.
C. Douville*, C.P. Chen, M. Ira, H. Schilder, D.T. Graves Boston University School of Dental Medicine Microbial pathogens are known to initiate the recruitment of inflammatory cells and the development of lesions of endodontic origin (LEOs). The purpose of this study was to evaluate the recruitment and role of mononuclear cells in response to challenge by endodontic pathogens. This was undertaken in two different models. The in vivo response of normal mice (n=6) to inoculation of the dental pulp with six putative endodontic pathogens was examined first. The results indicate that mononuclear cells are recruited in a time-dependent manner, with a statistically significant peak occuNing at 14 days after inoculation (p < 0.05). To investigate the role of host factors in mediating this recruitment, we examined the response to a specific endodontic pathogen in mice with targeted deletion of the monocyte chemoattractant protein-I (MCP- 1) gene, which was chosen because of its central role in several different pathophysiological responses. Mice were inoculated with P. gingivalis and the impact on osteoclast formation was compared between mice lacking a functional MCP-I gene and their normal counterparts. The results indicate that there is no significant difl'erence between mice lacking a functional MCP- 1 gene and their normal counterparts. We conclude that the MCP-1 gene does not contribute significantly to osteoclastogenesis, suggesting that bacteria-derived factors play a central rote in this process.
PRIP231 H u m a n pulpal or gingival fibroblasts attached to polyglycolic acid scaffolds survive and function in vivo. B Buurma*, K Gu, D Mooney, B Rutherford. The University of Michigan Autologous tissue grafting for the restoration of oral tissues is limited by several factors including the availability of sufficient donor tissue. One solution to this problem may be to develop substitute tissue grafts by attaching cultured autologous cells to scaffolds comprised of natural or synthetic polymers, developing the cell/scaffold contructs in vitro, and implanting them into a suitable site in vivo. We have shown that human dental pulp and gingival fibroblasts attach to nonwoven poly(glycolic acid) scaffolds, divide, and express genes thought to be associated with dentinogenesis (i.e. BMP-2, -4, OP-1, MSX-2, ActRI, B M P R - I A , -IB, -II, and type I collagen) in vitro. However, successful implantation had not been demonstrated. After 48 h in vitro, c e l l / s c a f f o l d constructs were implanted subdermally into immunodeficient mice. Histological examination of cell/scaffold constructs after three weeks in vivo revealed blood vessels distributed throughout. Cell/scaffold constructs contained mRNA for the human-specific Alu D N A sequence, human S-14 ribosomal protein, and all of the genes listed above. Human cells, immunopositive for human type I collagen and human prolyl 4-hydroxylase, were sparsely distributed throughout the cell/scaffold construct. Th~se data reveal that HPF and HGF attached to PGA scaff01~ pnd imolanted in vivo survive and exvress some markers of ¢gnnective tissue formation.
P~I 2_Y_l
An in vitro evaluation of five materials as chamber floor sealants in endodontically treated teeth. B.K. Elliott, A.K. Mickel, S.M.A. Chogle*
Case Western Reserve University Five restorative materials were evaluated for their ability to seal the chamber floor of endodontically treated teeth: amalgam with cavity varnish, Geristore ®,Geristore ®bonded with Tenure ~, Tetric Flow®bonded with Syntac®/Heliobond ®, and Syntac®/Heliobond ® alone. The root canal system of eighty-seven molars were cleaned, shaped, and obt,urated. The pulp chambers of the teeth were then filled with methylene blue dye under vacuum conditions and subsequently embedded in orthodontic resin. The apical extent of dye penetration was evaluated by incremental grinding of the teeth in an apical to coronal direction until dye was visualized under 2.5X magnification. The results indicated that the performance of dentin-bonded composites was more effective (P<0.001) in the prevention of dye penetration than either unbonded Geristore~ and especially amalgam with cavity varnish. Dentin-bonded flowable composite resins were effective in preventing the penetration of methylene blue dye. The elimination of coronal microleakage in endodonticallv treated teeth may improve the prognosis of root canal therapy. The use of a flowable composite with a dentin bonding agent as a chamber floor sealant allows visualization of the coronal gutta-percha, is able to seal cotton placed in a post preparation, is quick and simple to use, and will not interfere with the aims of the restorative dentist.
Vol. 25, No. 4, April 1999
P.%~] Growth inhibition of Streptococcus milleri and 223 Staphylococcus aureus in human serum and dental pulp after single oral dose of clindamycin hydrochioride. P.E. Scott, A.K. Mickel, E. Choi* Case Western Reserve University The purpose of this study was to determine if, when, and for how long, a single close of oral administered clindamycin hydrochloride would reach therapeutic concentration levels in the tooth and pulp and in the serum. 15 human subjects were studied. Each had a bicuspid or molar to be extracted. 12 subjects received a single, 150 mg oral dose of clindamycin hydrochloride at time intervals that varied from 45, 90, 135 and 180 minutes preextraction. Three subjects served as negative controls and received no drug prior to extraction. Following extraction, the tooth pulp and serum were sampled. An agar diffusion method was utilized which measured zones of inhibition to bacterial growth. S. milleri and S. aureus were used as test organisms. The mean peak concentration occurred at 90 minutes and was maintained at peak levels through 135 minutes. The ratio of pulp to serum concentration varied only slightly when Streptococcus and Staphylococcus were used as the test microbes: the ratio was 0.45:1 for S. milleri and 0.43:1 for S. aureus. The results of this study indicate that a therapeutic level of clindamycin hydrochloride was attained following a single oral dose of 150 my. Given the rapidity with which this occurred, administration of leading doses of clindamycin might be unnecessary in the treatment of pulp infections caused by susceptible microorganisms.
P~[ 2ZJ
M o n o n u c l e a r cell recruitment and development of lesions of endodontic origin.
C. Douville*, C.P. Chen, M. Ira, H. Schilder, D.T. Graves Boston University School of Dental Medicine Microbial pathogens are known to initiate the recruitment of inflammatory cells and the development of lesions of endodontic origin (LEOs). The purpose of this study was to evaluate the recruitment and role of mononuclear cells in response to challenge by endodontic pathogens. This was undertaken in two different models. The in vivo response of normal mice (n=6) to inoculation of the dental pulp with six putative endodontic pathogens was examined first. The results indicate that mononuclear cells are recruited in a time-dependent manner, with a statistically significant peak occuNing at 14 days after inoculation (p < 0.05). To investigate the role of host factors in mediating this recruitment, we examined the response to a specific endodontic pathogen in mice with targeted deletion of the monocyte chemoattractant protein-I (MCP- 1) gene, which was chosen because of its central role in several different pathophysiological responses. Mice were inoculated with P. gingivalis and the impact on osteoclast formation was compared between mice lacking a functional MCP-I gene and their normal counterparts. The results indicate that there is no significant difl'erence between mice lacking a functional MCP- 1 gene and their normal counterparts. We conclude that the MCP-1 gene does not contribute significantly to osteoclastogenesis, suggesting that bacteria-derived factors play a central rote in this process.