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A COMPARISON OF PARIETAL AND ILLIAC CREST BONE GRAFTS FOR ORBITAL RECONSTRUCTION INDIAN DENTAL ACADEMY

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Blowout # of the orbit most commonly involve the floor & medial wall. The displacement of the wall can have serious sequelae regarding function & appearance of the eye. In general , the volume of the orbit will change relative to the displacement of one or more walls. If the volume of the orbit relative to the volume of the intraorbital soft tissue contents the globe will sink inward & possibly downward. If the volume of the orbit is reduced it will project outward & possibly upward.

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Several theories have seen proposed to explain the effect of trauma on the orbit. In the hydraulic theory, a hard object strikes the soft tissue of the orbit & transfers pressures from these tissues to the orbit walls. The thinner walls then open like a trap door into an adjacent sinus, & the soft tissues are pushed through the defect. In another theory –BUCKLING THEORY, a force to the orbital rim causes the orbital wall to buckle, deforming them & the soft tissues. Despite the long term results of orbital reconstruction , there are cases in which the long term results & cosmetic outcomes may be different than after immediate postop. www.indiandentalacademy.com


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It is suggested that membranous bone grafts significantly under goes less resorption than the endocondral bone grafts when applied to the craniofacial skeleton & that membranous bone grafts should be used preferentially.

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PATIENTS AND METHODS 

From 1983 -1997--- 25 orbital reconstructions in 22 pts repaired with autogenous bone grafts were able to be evaluated. Follow up was scheduled for 1,2,3,6 & 12 months & measurements were obtained & recorded for as long as pts participated in the follow-up period. Of the 25, parietal bone graft is placed for 9 & 16 for iliac crest bone grafts. Illiac bone were used preferentially for larger defects. www.indiandentalacademy.com


All pts received grafts to the inferior wall, some had graft for the posterosuperior lat wall. Pre op & post op enophtalmos were measured using corneal projection with a Hertel exopthalometer & ruler ruler referenced to the lat orbital rim. Pre- & post op hypophthalmos, exophthalmos & diplopia was evaluated subjectively in 3 gaze of fields. Post surgery measures were scheduled for 1,2,3,6 & 12 months. Best values were between 3 – 7 months since by that time swelling would have been reduced & calues had been largely stabilized. www.indiandentalacademy.com


RESULTS 

There were 15 males & 7 females of total 25 # reconstruction. Age ranged from 19 – 57. Time initial injury to surgery ranged from 1 – 20 months, with a median of 4 months for cranial & 8 months for illiac graft. period of evaluation for cranial bone is 4 – 54 months & for illaic bone is 4 – 51 months . For cranial grafts the mean & SD showed 1.78 ± 1.20 mm, illic bone 1.37 ± 1.53mm. www.indiandentalacademy.com


Comparison of pre & post op showed that illiac bone graft has greatest reduction.  In enophthalmous- cranial group ,7 to 9 surgeries were successful, for illiac 15 of 16 were successful.  Hypohthalmous was difficult to evaluate because of statistical analysis. 

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Discussion ď ś

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Several authors have reported that free endocondral bone placed on the craniofacial skeleton resorb to a greater extent than free membranous grafts. Membranous bone graft maintain their volume better that endochondral bone graft when grafted on the rabbit snout. Membraneous bone tend to have a thicker cortex & a denser, thinner cancellous layer than endocondral bobe graft. www.indiandentalacademy.com


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Another important factor is the resorption in the method of fixation of the graft. Movement of the graft tends to decrease viability , & it is believed that rigid fixation of the onlay bone grafts will decrease resorption. It si also important to determine which factors were operationally important in the apparent lack of resorption of these grafts.

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A comparison of parietal and illiac crest bone/ dental implant courses by Indian dental academy