The aim of this study was to evaluate the mechanical effect over teeth and bone structures of surgically assisted rapid maxillary expansion (SARME) in photoelastic skull analogs by comparing stress produced during activation of a Bone-borne (BB) appliance and a tooth-borne (TB) appliance. Two photoelastic analogs were fabricated by use of birefringent materials to simulate an adult skull that contained teeth, bone and maxillary sinus. The BB was applied to the palatine bone and the TB appliance had bands cemented to the first premolars and first molars. SARME was simulated by subsequent cuts of the lateral maxillary wall, midpalatine suture and separation of the pterygomaxillary junction. After each osteotomy, the appliances were activated. Resulting stress patterns were recorded photographically in the field of a plane polariscope. Before any osteotomy, the activation of the TB appliance concentrated stress specially at the maxillary tuberosity and pterygoid plates. The BB appliance concentrated stress at the alveolar bone, but with less intensity than the TB appliance. No stress was seen over teeth. Stress was seen around the central incisors for both appliances. All three analogs showed similar distribution of stress throughout the skull. With consecutive activations following simulation of the osteotomies, there was a marked decrease in stress intensity throughout the analogs. In conclusion, Stress concentrates mostly over anchorage teeth for the TB appliance and alveolar bone for the BB appliance. BB appliance does not load teeth. Sectioning of all maxillary articulations, including separation of the pterygomaxillary junction, decreased stress over anchorage teeth.

Conflict of interest: None declared.