Movimiento dentario ortodóncico a través del hueso neoformado e inducido por biomateriales

Abstract

Aim: To prove if it is possible to move teeth orthodontically through the new vital bone created by osseoregeneration induced by graft materials. Material: Experimental animals: 28 minipigs of 15-22 months of age, divided in three groups. 4 of them was the control group, and 12 + 12 of them was included in each biomaterial experimental subgroup. Graft materials: OsteoGraf/N ( anorganic bovine bone matrix )( hydroxyapatite ), and Bioglass ( bioactive ceramic). Orthodontic materials: Individualized impression trims. Individualized tooth bands cemented in mandibular canine and in second permanent premolar as anchorage unit. Bands cemented on the firts permanent premolars with soldered hooks to insert NiTi coils of 100-125 gm. ( Sentalloy TM ). Method: Each animal was marked with a digital number (micro-chip). Always under total anaesthesia, we did the following procedure: T1.- Impression records to make casts models. Periapical Rx. Surgical technique was the lateral window approach in the edentulous region between the canine and the first premolar. Osteotomies were made leaving a bottom bony wall. The xenograft material of choice was packed into the cavity. Tension-free flap closure was accomplished with 3-0 silk sutures. T2.- (1 month) Place the orthodontic appliance. Radiographic control of bony healing. T3.- (2 months) Radiographic control. T4.- (6 months) Removed biopsies and were placed in 10% neutral buffered formalin (pH 7,4). The specimens were processed using a nondecalcified technique, consisted in an infiltration with a lightcuring embedding resin ( Technovit 7210 VLC ) and photo-polymerized. Afterwards, were cut and stained with hematoxylin-eosin, Masson trichromic, and Junqueira Picrosirius. Results: Vital bone formation for each experimental group was performed. This new bone is histologically like the cortical bone. During the orthodontic tooth movement the distal and the messial roots of the first premolar suffer an external lacunae reabsorption in the root apex. When the messial root begins to take contact with the new bone, appear a progressive and total destructive resorption of the root. The distal root did not present this destruction. There is not differences between the two experimental groups. The control group presents lacunae root resorption in the apex and in the pressure root face, normally associated at the orthodontic movement. Conclusion: In our long term experimental work, we have found that, it is possible to move teeth through the new bone induced by the xenograft materials we have employed, but a total root resorption appears without any repair reaction.