Effect of Substance P in Mandibular Osteotomies After Amputation of the Inferior Alveolar Nerve

Purpose

The aims of this experiment were to study the effect and possible mechanism of substance P (SP) in the mandibular osteotomy healing process through inferior alveolar nerve (IAN) amputation.

Materials and Methods

Thirty-two adult China white rabbits were randomly divided into 2 groups (experimental and control). An osteotomy in the left mandible was created and concomitantly the experimental group underwent IAN amputation. The rabbits were sacrificed 7, 14, 21, and 28 days after operation, and specimens were collected and stained with hematoxylin and eosin and for immunohistochemistry to observe the expression of SP in bone callus and the process of osteotomy healing. Semiquantitative analysis on immunohistochemically stained slices was performed using computer image analysis.

Results

There was a larger amount of fibrous callus formation, relatively immature woven bone callus, and a smaller proportion between matured bone callus and woven bone in the group subjected to IAN amputation than in the controls at each stage, especially in the late stages. Immunoreactivities of SP occurred weakly 7 and 14 days after operation and became stronger gradually in the late stage in the experimental group. Stronger immunoreactivities of SP occurred 7 and 14 days after operation and less on day 21 after trauma and became strongest on day 28 after trauma in the control group. The strongest immunoreactivities at each stage occurred on day 28 after trauma in both groups.

Conclusion

SP secreted by IAN may be very important to initiate and modulate the process of repair and remodeling of bone.