Arthur Ashman

New York University College of Dentistry, New York, New York, United States

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Publications (2)5.13 Total impact

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    ABSTRACT: Background: This report is the second part of the previously published study on the impact of light/chemical hardening technology and a newly formulated composite graft material for crestal augmentation during immediate implant placement. Methods: Light-hardened poly-methyl-methacrylate, poly-hydroxyl-ethyl-methacrylate, and calcium hydroxide plus polyanhydride (PPCH+PA) composite graft), PPCH graft alone, PA graft alone, were compared to each other and to a no graft control group. All mandibular premolar teeth were extracted; a total of 48 implants were placed into sockets of the mesial roots in three minipigs. Crestal areas and intrabony spaces were randomly augmented with graft materials or left untreated. Distal sockets not receiving implants and the sockets of first molars (n=60) were randomly treated with one of graft materials or left empty. In addition, two molar sockets were treated with original PMMA/PHEMA and calcium hydroxide (PPCH) graft material. Quantitative microcomputed tomography (µCT) was used to assess alveolar bone structure and tissue compositions following crestal augmentations. Histological evaluations included descriptive histology to assess the peri-implant wound healing as well as histomorphometric measurements to determine bone-to-implant contact (BIC). Results: Although PPCH alone showed the least impact on trabecular bone formation, both trabecular and cortical bone measurements by µCT did not reveal any significant differences between the groups. Sites augmented with PPCH+PA resulted in significantly greater BIC surface than PPCH alone and no graft treated implants (p<0.05) histologically. Villanueva-stained sections showed complete bone formation between bone and implant surface in the PPCH+PA group, while sites without augmentation showed large gaps between bone and implant surfaces indicating a slower bone apposition and less BIC surface compared to all other groups. Similar to implant sections, all materials showed positive outcome on trabecular and cortical bone formation in extraction sockets with an intact crestal cortical bone. Conclusion: Histological evaluations supported the earlier findings on implant stability and function and confirmed that PPCH+PA provides a greater BIC contact with a well-organized implant-bone interface and is useful in crestal augmentation during immediate implant placement.
    Journal of Periodontology 02/2014; 85(9). DOI:10.1902/jop.2014.120424 · 2.57 Impact Factor
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    ABSTRACT: The present study is designed as a proof-of-concept study to evaluate light/chemical hardening technology and a newly formulated polymethylmethacrylate, polyhydroxyethylmethacrylate, and calcium hydroxide (PPCH) plus polyanhydride (PA) (PPCH-PA) composite graft material as a bone substitute compared to positive and negative controls in a minipig model. PPCH-PA (composite graft); PPCH alone (positive control), PA alone (positive control), and no graft (negative control) were compared. Four mandibular premolar teeth per quadrant were extracted; a total of 48 implants were placed into sockets in three minipigs. Abutments were placed protruding into the oral cavity 4 mm in height for immediate loading. Crestal areas and intrabony spaces were filled with PPCH-PA, PPCH, or PA using a three-phase delivery system in which all graft materials were hardened by a light cure. In the negative control group, implant sites were left untreated. At 12 weeks, block sections containing implants were obtained. Evaluations included periodontal probing, pullout-force load, and stability measurements to determine implant stability, radiographs to examine bone levels, and scanning electron microscopy (SEM)-energy-dispersed spectroscopy to determine bone-to-implant contact. Probing measurements did not reveal any pathologic pocket formation or bone loss. Radiographs revealed that immediate implant placement and loading resulted in bone at or slightly apical to the first thread of the implant in all groups at 12 weeks. Stability test values showed a relative clinical stability for all implants (range: -7 to +1); however, implants augmented with PPCH-PA exhibited a statistically significantly greater stability compared to all other groups (P <0.05). The newly formed bone in PPCH-PA-treated sites was well organized with less marrow spaces and well-distributed osteocytes. SEM revealed a tighter implant-socket interface in the PPCH-PA group compared to other groups with reduced microfissures and implant-bone interface fractures during pullout testing, whereas implants treated with PA or no graft showed ≈ 10-μm microfissures between the implant and bone with fractures of the intrathread bone. The newly formulated chemically hardened graft material PPCH-PA was useful in immediate implant placement after tooth extraction and resulted in greater stability and a well-organized implant-bone interface with immediate loading, especially in those areas where cancellous bone was present. The results of this proof-of-concept study warranted further research investigating different healing times and longer durations.
    Journal of Periodontology 02/2011; 82(9):1339-52. DOI:10.1902/jop.2011.100617 · 2.57 Impact Factor