Date of Award


Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)



First Advisor

Maria J. Troulis

Second Advisor

Robert D. Stevenson

Third Advisor

Linda S. Huang


PURPOSE: To evaluate bone and soft tissue healing at rates faster than 1 mm/day following automated, continuous, curvilinear distraction osteogenesis in a minipig model.

MATERIALS AND METHODS: 10 Yucatan minipigs in the mixed-dentition stage underwent automated, continuous, curvilinear DO of the right mandible. Animals were distracted 12 mm at rates of 1.5 (n=5) and 3.0 mm/day (n=5) followed by 24 days of fixation. The animals were sacrificed and bone and soft tissue healing was evaluated. A semi-quantitative scale was used to assess the ex vivo clinical appearance of the distraction gap (3=osteotomy not visible; 2=50% visible; 0=100% visible), stability (3=no mobility; 2 and 1=mobility in 1 plane or 2 planes, respectively; 0=mobility in 3 planes), and radiographic density (4=100% of gap opaque; 3=>75%; 2=50% to 75%; 1=

RESULTS: Automated, continuous DO at 1.5 mm/day and 3.0 mm/day had similar bone formation compared to the discontinuous, 1 mm/day positive control. Continuous DO at 1.5 mm/day had significantly increased scores for appearance and radiographic density than the discontinuous 4 mm/day group. The continuous DO 3 mm/day group had significantly greater appearance and radiographic density scores compared with the discontinuous 4 mm/day groups and higher stability compared to the discontinuous 2 and 4 mm/day groups. PSA occupied by bone for the continuous 1.5, 3.0, and discontinuous DO at 1 mm/day were similar (1.5 mm/day PSA=64.36±5.87, 3.0 mm/day PSA=63.83±3.37, and 1.0 mm/day PSA=64.89±0.56), but less than the nonoperated side (PSA=84.67±0.86). PSA occupied by cartilage and hematoma in all groups was minimal (< 1.1%). The digastric muscles had no abnormal tissue or inflammation and PAX7, MyoD, and PCNA expression had returned to baseline levels.

CONCLUSIONS: Results of this study indicate that bone fill of the continuous distraction wound at rates of 1.5 and 3 mm/day was similar to that of discontinuous DO at 1 mm/day. Continuous DO at rates of 1.5 and 3.0 mm/day allows nearly identical PSA occupied by bone when compared to discontinuous DO at 1 mm/day. Digastric muscles exhibited no deleterious effects caused by DO. This supports the potential to shorten treatment time for management of craniofacial deformities.


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