# Functional Evaluation of a Novel Multi-Axial Alveolar Distractor--Preliminary In Vivo Animal Study
## 4 Discussion
Therefore, the bone growth total length at the angulus following distraction was directly calculated by measuring the bending steel wire attached to the growing bone surface. A fracture test was conducted on the newly formed bone to compare it with the intact bone. Comparing the bone growth geometric shape observed in Groups TMB, TM and TC at the mandible angulus showed that the left and right mandibles were symmetrical to the axis of the incisors in Group TC (control group). Both Groups TMB and TM presented bone growth with a tendency toward the buccal outer side at the mandible angulus. The bone outer length thickness in Group TMB was thicker than that of Group TM. The bone growth geometric shape of Group TMB was observed to develop obviously more outward than that of the bowl, while the corresponding bone shape of Group TM was relatively flat. The difference in bone growth morphology may be caused by the fact that Group TMB has more than 15\({}^{\circ}\) to the mesial side in distraction than Group TM. This phenomenon can also be explained in the bone growth mechanical strength test. The fracture strength of Group TMB was higher than that of Group TM. The mechanical fracture test found that the fracture strength at the distraction side was lower than that of the bone on the normal (control) side. The result showed that the distraction bone to normal bone tensile strength percentages were 57% and 39% for Groups TMB and TM, respectively. Since the bone at the osteotomy region gradually healed during distraction, the bone healing undergoes a fragile period (formation period of the epiphysis) and an intensity increase period (reconstruction period) to return to its original intact strength. However, bone growth affects its healing state due to factors such as age, constitution and healing time. A review study indicated that the consolidation phase duration is a major factor that influences the overall treatment time and primary stability of implants placed in the distracted bone [13]. Although, a histochemical study in rabbits by [PERSON] et al. indicated no major morphological differences between the bone appearance at 2 and 6 months, i.e., bone maturation in rabbits, around titanium implants at least 2 months old [24]. However, [PERSON] and [PERSON] reported that a period of 12 weeks is sufficient for bone maturation ready for dental implantation figure [25]. Bone augmentation has been verified with clinical, histological and radiographic evidence that bone distraction is a predictable and reliable surgical method. Therefore, the consolidation phase in our study lasted only 8 weeks, suggesting that longer consolidation is required for bones to heal to their original bone strength. The mechanical strength of the newly formed bone can be improved. As mentioned in our previous article [18], the ball-and-socket joint design dimension is slightly larger than that of the commonly used hinge-type distractors and may interfere with flap closure, further leading to dehiscence. This could be overcome using a flap design with adequate periosteum release and modifying the ball-and-socket mechanical design/manufacturing process in the future.