Methods of forming releasable palatal expanders

A method of designing a palatal expander for a patient, the method comprising:

• forming a digital model of the palatal expander based on a scan of the patient's upper dental arch, the digital model comprising two tooth engagement regions and a palatal region connecting the tooth engagement regions, wherein forming the digital model comprises:
• forming the palatal region such that a corresponding palatal region of the palatal expander is configured to apply a lateral force across the patient's palate when corresponding tooth engagement regions of the palatal expander are worn over the patient's upper teeth;
• forming attachment regions on buccal sides of each of the tooth engagement region, the attachment regions shaped and sized to engage with attachments bonded to the patient's upper teeth;
• determining a position of at least one breach region in the digital model, the position is determined based on avoid interference with the lateral force across the patient's palate and/or forces applied to move one or more of the patient's upper teeth according to a treatment plan;
• and
• forming the at least one breach region of the digital model corresponding to a thinned region of the palatal expander that extends anteriorly to posteriorly in the palatal region or an occlusal portion of one or both of the tooth engagement regions, wherein a corresponding at least one breach region of the palatal expander is configured to breach or bend when a pulling force is applied to one or both of the tooth engagement regions such that one or both of the attachment regions are detached from respective attachments.

A method of designing a series of palatal expanders for treating a patient, the method comprising:

• forming a series of digital models corresponding to the series of palatal expanders based on a scan of the patient's upper dental arch, each digital model of the series of digital models corresponding to a stage of a treatment plan, each the digital model comprising two tooth engagement regions and a palatal region connecting the tooth engagement regions, wherein forming each digital model comprises:
• forming the palatal region such that a corresponding palatal region of the palatal expander is configured to apply a lateral force across the patient's palate when corresponding tooth engagement regions of the palatal expander are worn over the patient's upper teeth;
• forming attachment regions on buccal sides of each of the tooth engagement region, the attachment regions shaped and sized to engage with attachments bonded to the patient's upper teeth;
• and
• forming at least one breach region of the digital model corresponding to a thinned region of the palatal expander that extends anteriorly to posteriorly in the palatal region or an occlusal portion of one or both of the tooth engagement regions, wherein a corresponding at least one breach region of the palatal expander is configured to breach or bend when a pulling force is applied to one or both of the tooth engagement regions such that one or both of the attachment regions are detached from respective attachments.