The aim of this study was evaluate the mechanical effect over teeth and bone structures of surgically assisted rapid maxillary expansion (SARME) in photoelastic skull analogs by observing stress produced during Hyrax-type activation using different anchorages. Three photoelastic analogs were fabricated by use of birefringent materials to simulate an adult skull that contained teeth, bone and maxillary sinus. Three hyrax-type appliances were applied to the anchor teeth and incrementally activated. One hyrax-type appliance had bands cemented to the first premolars and first molars, the second had bands cemented to the canines and first molars and the third had bands cemented to the canines and second 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. The activation of the appliances distributed stress through the anchoring teeth to the alveolar bone. Stress concentrated at the maxillary tuberosity and pterygoid plates and around the central incisors. All three analogs showed similar distribution of stress after activation throughout the skull. With consecutive activations following the osteotomies, there was a marked decrease in stress intensity. In conclusion, stress concentrates mostly over the anchorage teeth. The design of the appliance does not influence the distribution of stress along the anterior and posterior areas of the maxilla. Sectioning of all maxillary articulations caused a decrease in stress over anchorage teeth.

Conflict of interest: None declared.